prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  add axis labels to ITER parameters plot
  The ITER parameters plot [here](http://docs.plasmapy.org/en/stable/auto_examples/plot_physics.html#sphx-glr-auto-examples-plot-physics-py) could use some labels and units in said labels.
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `plasmapy/__init__.py`
  Content:
  ```
  1 # Licensed under a 3-clause BSD style license - see LICENSE.rst
  2 
  3 # Packages may add whatever they like to this file, but
  4 # should keep this content at the top.
  5 # ----------------------------------------------------------------------------
  6 from ._base_init import *
  7 # ----------------------------------------------------------------------------
  8 
  9 # Enforce Python version check during package import.
  10 # This is the same check as the one at the top of setup.py
  11 import sys
  12 
  13 __name__ = "plasmapy"
  14 
  15 __doc__ = ("A community-developed and community-driven open source "
  16            "core Python package for plasma physics.")
  17 
  18 
  19 class UnsupportedPythonError(Exception):
  20     pass
  21 
  22 
  23 if sys.version_info < tuple((int(val) for val in "3.6".split('.'))):
  24     raise UnsupportedPythonError("plasmapy does not support Python < {}".format(3.6))
  25 
  26 if not _ASTROPY_SETUP_:
  27     # For egg_info test builds to pass, put package imports here.
  28     from . import atomic
  29     from . import classes
  30     from . import constants
  31     from . import diagnostics
  32     from . import mathematics
  33     from . import physics
  34     from . import utils
  35 
  36 __citation__ = """@misc{plasmapy_community_2018_1238132,
  37   author       = {PlasmaPy Community and
  38                   Murphy, Nicholas A. and
  39                   Leonard, Andrew J. and
  40                   Sta\'nczak, Dominik and
  41                   Kozlowski, Pawel M. and
  42                   Langendorf, Samuel J. and
  43                   Haggerty, Colby C. and
  44                   Beckers, Jasper P. and
  45                   Mumford, Stuart J. and
  46                   Parashar, Tulasi N. and
  47                   Huang, Yi-Min},
  48   title        = {{PlasmaPy: an open source community-developed 
  49                    Python package for plasma physics}},
  50   month        = apr,
  51   year         = 2018,
  52   doi          = {10.5281/zenodo.1238132},
  53   url          = {https://doi.org/10.5281/zenodo.1238132}
  54 }"""
  55
  ```
  
  Path: `plasmapy/examples/plot_physics.py`
  Content:
  ```
  1 """
  2 Analysing ITER parameters
  3 =========================
  4 
  5 Let's try to look at ITER plasma conditions using the `physics` subpackage.
  6 """
  7 
  8 from astropy import units as u
  9 from plasmapy import physics
  10 import matplotlib.pyplot as plt
  11 import numpy as np
  12 from mpl_toolkits.mplot3d import Axes3D
  13 
  14 ######################################################
  15 # The radius of electric field shielding clouds, also known as the Debye length,
  16 # would be
  17 
  18 electron_temperature = 8.8 * u.keV
  19 electron_concentration = 10.1e19 / u.m**3
  20 print(physics.Debye_length(electron_temperature, electron_concentration))
  21 
  22 ############################################################
  23 # Note that we can also neglect the unit for the concentration, as
  24 # 1/m^3 is the a standard unit for this kind of Quantity:
  25 
  26 print(physics.Debye_length(electron_temperature, 10.1e19))
  27 
  28 ############################################################
  29 # Assuming the magnetic field as 5.3 Teslas (which is the value at the major
  30 # radius):
  31 
  32 B = 5.3 * u.T
  33 
  34 print(physics.gyrofrequency(B, particle='e'))
  35 
  36 print(physics.gyroradius(B, T_i=electron_temperature, particle='e'))
  37 
  38 ######################################################################
  39 # The electron inertial length would be
  40 print(physics.inertial_length(electron_concentration, particle='e'))
  41 
  42 ######################################################################
  43 # In these conditions, they should reach thermal velocities of about
  44 print(physics.thermal_speed(T=electron_temperature, particle='e'))
  45 
  46 ######################################################################
  47 # And the Langmuir wave plasma frequency should be on the order of
  48 print(physics.plasma_frequency(electron_concentration))
  49 
  50 ############################################################
  51 # Let's try to recreate some plots and get a feel for some of these quantities.
  52 
  53 n_e = np.logspace(4, 30, 100) / u.m**3
  54 plt.plot(n_e, physics.plasma_frequency(n_e))
  55 plt.scatter(
  56     electron_concentration,
  57     physics.plasma_frequency(electron_concentration))
  58
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/plasmapy/__init__.py b/plasmapy/__init__.py
  --- a/plasmapy/__init__.py
  +++ b/plasmapy/__init__.py
  @@ -33,6 +33,29 @@
       from . import physics
       from . import utils
   
  +def online_help(query):
  +    """
  +    Search the online PlasmaPy documentation for the given query from plasmapy.org
  +    Opens the results in the default web browser.
  +    Requires an active Internet connection.
  +    Redirects to Astropy.units in case of query 'unit' or 'units'
  +
  +    Parameters
  +    ----------
  +    query : str
  +        The search query.
  +    """
  +    from urllib.parse import urlencode
  +    import webbrowser
  +
  +    url = 'http://docs.plasmapy.org/en/stable/search.html?\
  +    {0}&check_keywords=yes&area=default'.format(urlencode({'q': query}))
  +
  +    if(query.lower() in ('unit', 'units')):
  +        url = 'http://docs.astropy.org/en/stable/units/'
  +
  +    webbrowser.open(url)
  +
   __citation__ = """@misc{plasmapy_community_2018_1238132,
     author       = {PlasmaPy Community and
                     Murphy, Nicholas A. and
  @@ -51,4 +74,4 @@
     year         = 2018,
     doi          = {10.5281/zenodo.1238132},
     url          = {https://doi.org/10.5281/zenodo.1238132}
  -}"""
  +}"""
  \ No newline at end of file
  diff --git a/plasmapy/examples/plot_physics.py b/plasmapy/examples/plot_physics.py
  --- a/plasmapy/examples/plot_physics.py
  +++ b/plasmapy/examples/plot_physics.py
  @@ -55,3 +55,6 @@
   plt.scatter(
       electron_concentration,
       physics.plasma_frequency(electron_concentration))
  +plt.xlabel("Electron Concentration (m^-3)")
  +plt.ylabel("Langmuir Wave Plasma Frequency (rad/s)")
  +plt.show()
  
verification_info: {"golden_diff": "diff --git a/plasmapy/__init__.py b/plasmapy/__init__.py\n--- a/plasmapy/__init__.py\n+++ b/plasmapy/__init__.py\n@@ -33,6 +33,29 @@\n     from . import physics\n     from . import utils\n \n+def online_help(query):\n+    \"\"\"\n+    Search the online PlasmaPy documentation for the given query from plasmapy.org\n+    Opens the results in the default web browser.\n+    Requires an active Internet connection.\n+    Redirects to Astropy.units in case of query 'unit' or 'units'\n+\n+    Parameters\n+    ----------\n+    query : str\n+        The search query.\n+    \"\"\"\n+    from urllib.parse import urlencode\n+    import webbrowser\n+\n+    url = 'http://docs.plasmapy.org/en/stable/search.html?\\\n+    {0}&check_keywords=yes&area=default'.format(urlencode({'q': query}))\n+\n+    if(query.lower() in ('unit', 'units')):\n+        url = 'http://docs.astropy.org/en/stable/units/'\n+\n+    webbrowser.open(url)\n+\n __citation__ = \"\"\"@misc{plasmapy_community_2018_1238132,\n   author       = {PlasmaPy Community and\n                   Murphy, Nicholas A. and\n@@ -51,4 +74,4 @@\n   year         = 2018,\n   doi          = {10.5281/zenodo.1238132},\n   url          = {https://doi.org/10.5281/zenodo.1238132}\n-}\"\"\"\n+}\"\"\"\n\\ No newline at end of file\ndiff --git a/plasmapy/examples/plot_physics.py b/plasmapy/examples/plot_physics.py\n--- a/plasmapy/examples/plot_physics.py\n+++ b/plasmapy/examples/plot_physics.py\n@@ -55,3 +55,6 @@\n plt.scatter(\n     electron_concentration,\n     physics.plasma_frequency(electron_concentration))\n+plt.xlabel(\"Electron Concentration (m^-3)\")\n+plt.ylabel(\"Langmuir Wave Plasma Frequency (rad/s)\")\n+plt.show()\n", "issue": "add axis labels to ITER parameters plot\nThe ITER parameters plot [here](http://docs.plasmapy.org/en/stable/auto_examples/plot_physics.html#sphx-glr-auto-examples-plot-physics-py) could use some labels and units in said labels.\n", "before_files": [{"content": "# Licensed under a 3-clause BSD style license - see LICENSE.rst\n\n# Packages may add whatever they like to this file, but\n# should keep this content at the top.\n# ----------------------------------------------------------------------------\nfrom ._base_init import *\n# ----------------------------------------------------------------------------\n\n# Enforce Python version check during package import.\n# This is the same check as the one at the top of setup.py\nimport sys\n\n__name__ = \"plasmapy\"\n\n__doc__ = (\"A community-developed and community-driven open source \"\n           \"core Python package for plasma physics.\")\n\n\nclass UnsupportedPythonError(Exception):\n    pass\n\n\nif sys.version_info < tuple((int(val) for val in \"3.6\".split('.'))):\n    raise UnsupportedPythonError(\"plasmapy does not support Python < {}\".format(3.6))\n\nif not _ASTROPY_SETUP_:\n    # For egg_info test builds to pass, put package imports here.\n    from . import atomic\n    from . import classes\n    from . import constants\n    from . import diagnostics\n    from . import mathematics\n    from . import physics\n    from . import utils\n\n__citation__ = \"\"\"@misc{plasmapy_community_2018_1238132,\n  author       = {PlasmaPy Community and\n                  Murphy, Nicholas A. and\n                  Leonard, Andrew J. and\n                  Sta\\'nczak, Dominik and\n                  Kozlowski, Pawel M. and\n                  Langendorf, Samuel J. and\n                  Haggerty, Colby C. and\n                  Beckers, Jasper P. and\n                  Mumford, Stuart J. and\n                  Parashar, Tulasi N. and\n                  Huang, Yi-Min},\n  title        = {{PlasmaPy: an open source community-developed \n                   Python package for plasma physics}},\n  month        = apr,\n  year         = 2018,\n  doi          = {10.5281/zenodo.1238132},\n  url          = {https://doi.org/10.5281/zenodo.1238132}\n}\"\"\"\n", "path": "plasmapy/__init__.py"}, {"content": "\"\"\"\nAnalysing ITER parameters\n=========================\n\nLet's try to look at ITER plasma conditions using the `physics` subpackage.\n\"\"\"\n\nfrom astropy import units as u\nfrom plasmapy import physics\nimport matplotlib.pyplot as plt\nimport numpy as np\nfrom mpl_toolkits.mplot3d import Axes3D\n\n######################################################\n# The radius of electric field shielding clouds, also known as the Debye length,\n# would be\n\nelectron_temperature = 8.8 * u.keV\nelectron_concentration = 10.1e19 / u.m**3\nprint(physics.Debye_length(electron_temperature, electron_concentration))\n\n############################################################\n# Note that we can also neglect the unit for the concentration, as\n# 1/m^3 is the a standard unit for this kind of Quantity:\n\nprint(physics.Debye_length(electron_temperature, 10.1e19))\n\n############################################################\n# Assuming the magnetic field as 5.3 Teslas (which is the value at the major\n# radius):\n\nB = 5.3 * u.T\n\nprint(physics.gyrofrequency(B, particle='e'))\n\nprint(physics.gyroradius(B, T_i=electron_temperature, particle='e'))\n\n######################################################################\n# The electron inertial length would be\nprint(physics.inertial_length(electron_concentration, particle='e'))\n\n######################################################################\n# In these conditions, they should reach thermal velocities of about\nprint(physics.thermal_speed(T=electron_temperature, particle='e'))\n\n######################################################################\n# And the Langmuir wave plasma frequency should be on the order of\nprint(physics.plasma_frequency(electron_concentration))\n\n############################################################\n# Let's try to recreate some plots and get a feel for some of these quantities.\n\nn_e = np.logspace(4, 30, 100) / u.m**3\nplt.plot(n_e, physics.plasma_frequency(n_e))\nplt.scatter(\n    electron_concentration,\n    physics.plasma_frequency(electron_concentration))\n", "path": "plasmapy/examples/plot_physics.py"}], "after_files": [{"content": "# Licensed under a 3-clause BSD style license - see LICENSE.rst\n\n# Packages may add whatever they like to this file, but\n# should keep this content at the top.\n# ----------------------------------------------------------------------------\nfrom ._base_init import *\n# ----------------------------------------------------------------------------\n\n# Enforce Python version check during package import.\n# This is the same check as the one at the top of setup.py\nimport sys\n\n__name__ = \"plasmapy\"\n\n__doc__ = (\"A community-developed and community-driven open source \"\n           \"core Python package for plasma physics.\")\n\n\nclass UnsupportedPythonError(Exception):\n    pass\n\n\nif sys.version_info < tuple((int(val) for val in \"3.6\".split('.'))):\n    raise UnsupportedPythonError(\"plasmapy does not support Python < {}\".format(3.6))\n\nif not _ASTROPY_SETUP_:\n    # For egg_info test builds to pass, put package imports here.\n    from . import atomic\n    from . import classes\n    from . import constants\n    from . import diagnostics\n    from . import mathematics\n    from . import physics\n    from . import utils\n\ndef online_help(query):\n    \"\"\"\n    Search the online PlasmaPy documentation for the given query from plasmapy.org\n    Opens the results in the default web browser.\n    Requires an active Internet connection.\n    Redirects to Astropy.units in case of query 'unit' or 'units'\n\n    Parameters\n    ----------\n    query : str\n        The search query.\n    \"\"\"\n    from urllib.parse import urlencode\n    import webbrowser\n\n    url = 'http://docs.plasmapy.org/en/stable/search.html?\\\n    {0}&check_keywords=yes&area=default'.format(urlencode({'q': query}))\n\n    if(query.lower() in ('unit', 'units')):\n        url = 'http://docs.astropy.org/en/stable/units/'\n\n    webbrowser.open(url)\n\n__citation__ = \"\"\"@misc{plasmapy_community_2018_1238132,\n  author       = {PlasmaPy Community and\n                  Murphy, Nicholas A. and\n                  Leonard, Andrew J. and\n                  Sta\\'nczak, Dominik and\n                  Kozlowski, Pawel M. and\n                  Langendorf, Samuel J. and\n                  Haggerty, Colby C. and\n                  Beckers, Jasper P. and\n                  Mumford, Stuart J. and\n                  Parashar, Tulasi N. and\n                  Huang, Yi-Min},\n  title        = {{PlasmaPy: an open source community-developed \n                   Python package for plasma physics}},\n  month        = apr,\n  year         = 2018,\n  doi          = {10.5281/zenodo.1238132},\n  url          = {https://doi.org/10.5281/zenodo.1238132}\n}\"\"\"", "path": "plasmapy/__init__.py"}, {"content": "\"\"\"\nAnalysing ITER parameters\n=========================\n\nLet's try to look at ITER plasma conditions using the `physics` subpackage.\n\"\"\"\n\nfrom astropy import units as u\nfrom plasmapy import physics\nimport matplotlib.pyplot as plt\nimport numpy as np\nfrom mpl_toolkits.mplot3d import Axes3D\n\n######################################################\n# The radius of electric field shielding clouds, also known as the Debye length,\n# would be\n\nelectron_temperature = 8.8 * u.keV\nelectron_concentration = 10.1e19 / u.m**3\nprint(physics.Debye_length(electron_temperature, electron_concentration))\n\n############################################################\n# Note that we can also neglect the unit for the concentration, as\n# 1/m^3 is the a standard unit for this kind of Quantity:\n\nprint(physics.Debye_length(electron_temperature, 10.1e19))\n\n############################################################\n# Assuming the magnetic field as 5.3 Teslas (which is the value at the major\n# radius):\n\nB = 5.3 * u.T\n\nprint(physics.gyrofrequency(B, particle='e'))\n\nprint(physics.gyroradius(B, T_i=electron_temperature, particle='e'))\n\n######################################################################\n# The electron inertial length would be\nprint(physics.inertial_length(electron_concentration, particle='e'))\n\n######################################################################\n# In these conditions, they should reach thermal velocities of about\nprint(physics.thermal_speed(T=electron_temperature, particle='e'))\n\n######################################################################\n# And the Langmuir wave plasma frequency should be on the order of\nprint(physics.plasma_frequency(electron_concentration))\n\n############################################################\n# Let's try to recreate some plots and get a feel for some of these quantities.\n\nn_e = np.logspace(4, 30, 100) / u.m**3\nplt.plot(n_e, physics.plasma_frequency(n_e))\nplt.scatter(\n    electron_concentration,\n    physics.plasma_frequency(electron_concentration))\nplt.xlabel(\"Electron Concentration (m^-3)\")\nplt.ylabel(\"Langmuir Wave Plasma Frequency (rad/s)\")\nplt.show()\n", "path": "plasmapy/examples/plot_physics.py"}]}