We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
[BUG] Build documentation fails if dipy is not installed


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `nipype/interfaces/dipy/base.py`
Content:
```
1 # -*- coding: utf-8 -*-
2 """ Base interfaces for dipy """
3 import os.path as op
4 import numpy as np
5 from nipype.interfaces.base import (traits, File, isdefined,
6                                     BaseInterface, BaseInterfaceInputSpec)
7 from ... import logging
8 
9 IFLOGGER = logging.getLogger('interface')
10 
11 HAVE_DIPY = True
12 try:
13     import dipy
14 except ImportError:
15     HAVE_DIPY = False
16 
17 
18 def no_dipy():
19     """ Check if dipy is available """
20     global HAVE_DIPY
21     return not HAVE_DIPY
22 
23 
24 def dipy_version():
25     """ Check dipy version """
26     if no_dipy():
27         return None
28 
29     return dipy.__version__
30 
31 
32 class DipyBaseInterface(BaseInterface):
33 
34     """
35     A base interface for py:mod:`dipy` computations
36     """
37     def __init__(self, **inputs):
38         if no_dipy():
39             IFLOGGER.error('dipy was not found')
40             # raise ImportError('dipy was not found')
41         super(DipyBaseInterface, self).__init__(**inputs)
42 
43 
44 class DipyBaseInterfaceInputSpec(BaseInterfaceInputSpec):
45     in_file = File(exists=True, mandatory=True, desc=('input diffusion data'))
46     in_bval = File(exists=True, mandatory=True, desc=('input b-values table'))
47     in_bvec = File(exists=True, mandatory=True, desc=('input b-vectors table'))
48     b0_thres = traits.Int(700, usedefault=True, desc=('b0 threshold'))
49     out_prefix = traits.Str(desc=('output prefix for file names'))
50 
51 
52 class DipyDiffusionInterface(DipyBaseInterface):
53 
54     """
55     A base interface for py:mod:`dipy` computations
56     """
57     input_spec = DipyBaseInterfaceInputSpec
58 
59     def _get_gradient_table(self):
60         bval = np.loadtxt(self.inputs.in_bval)
61         bvec = np.loadtxt(self.inputs.in_bvec).T
62         from dipy.core.gradients import gradient_table
63         gtab = gradient_table(bval, bvec)
64 
65         gtab.b0_threshold = self.inputs.b0_thres
66         return gtab
67 
68     def _gen_filename(self, name, ext=None):
69         fname, fext = op.splitext(op.basename(self.inputs.in_file))
70         if fext == '.gz':
71             fname, fext2 = op.splitext(fname)
72             fext = fext2 + fext
73 
74         if not isdefined(self.inputs.out_prefix):
75             out_prefix = op.abspath(fname)
76         else:
77             out_prefix = self.inputs.out_prefix
78 
79         if ext is None:
80             ext = fext
81 
82         return out_prefix + '_' + name + ext
83
```
--- 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()

```

diff --git a/nipype/interfaces/dipy/base.py b/nipype/interfaces/dipy/base.py
--- a/nipype/interfaces/dipy/base.py
+++ b/nipype/interfaces/dipy/base.py
@@ -36,7 +36,7 @@
     """
     def __init__(self, **inputs):
         if no_dipy():
-            IFLOGGER.error('dipy was not found')
+            IFLOGGER.warn('dipy was not found')
             # raise ImportError('dipy was not found')
         super(DipyBaseInterface, self).__init__(**inputs)

{"golden_diff": "diff --git a/nipype/interfaces/dipy/base.py b/nipype/interfaces/dipy/base.py\n--- a/nipype/interfaces/dipy/base.py\n+++ b/nipype/interfaces/dipy/base.py\n@@ -36,7 +36,7 @@\n     \"\"\"\n     def __init__(self, **inputs):\n         if no_dipy():\n-            IFLOGGER.error('dipy was not found')\n+            IFLOGGER.warn('dipy was not found')\n             # raise ImportError('dipy was not found')\n         super(DipyBaseInterface, self).__init__(**inputs)\n", "issue": "[BUG] Build documentation fails if dipy is not installed\n\n", "before_files": [{"content": "# -*- coding: utf-8 -*-\n\"\"\" Base interfaces for dipy \"\"\"\nimport os.path as op\nimport numpy as np\nfrom nipype.interfaces.base import (traits, File, isdefined,\n                                    BaseInterface, BaseInterfaceInputSpec)\nfrom ... import logging\n\nIFLOGGER = logging.getLogger('interface')\n\nHAVE_DIPY = True\ntry:\n    import dipy\nexcept ImportError:\n    HAVE_DIPY = False\n\n\ndef no_dipy():\n    \"\"\" Check if dipy is available \"\"\"\n    global HAVE_DIPY\n    return not HAVE_DIPY\n\n\ndef dipy_version():\n    \"\"\" Check dipy version \"\"\"\n    if no_dipy():\n        return None\n\n    return dipy.__version__\n\n\nclass DipyBaseInterface(BaseInterface):\n\n    \"\"\"\n    A base interface for py:mod:`dipy` computations\n    \"\"\"\n    def __init__(self, **inputs):\n        if no_dipy():\n            IFLOGGER.error('dipy was not found')\n            # raise ImportError('dipy was not found')\n        super(DipyBaseInterface, self).__init__(**inputs)\n\n\nclass DipyBaseInterfaceInputSpec(BaseInterfaceInputSpec):\n    in_file = File(exists=True, mandatory=True, desc=('input diffusion data'))\n    in_bval = File(exists=True, mandatory=True, desc=('input b-values table'))\n    in_bvec = File(exists=True, mandatory=True, desc=('input b-vectors table'))\n    b0_thres = traits.Int(700, usedefault=True, desc=('b0 threshold'))\n    out_prefix = traits.Str(desc=('output prefix for file names'))\n\n\nclass DipyDiffusionInterface(DipyBaseInterface):\n\n    \"\"\"\n    A base interface for py:mod:`dipy` computations\n    \"\"\"\n    input_spec = DipyBaseInterfaceInputSpec\n\n    def _get_gradient_table(self):\n        bval = np.loadtxt(self.inputs.in_bval)\n        bvec = np.loadtxt(self.inputs.in_bvec).T\n        from dipy.core.gradients import gradient_table\n        gtab = gradient_table(bval, bvec)\n\n        gtab.b0_threshold = self.inputs.b0_thres\n        return gtab\n\n    def _gen_filename(self, name, ext=None):\n        fname, fext = op.splitext(op.basename(self.inputs.in_file))\n        if fext == '.gz':\n            fname, fext2 = op.splitext(fname)\n            fext = fext2 + fext\n\n        if not isdefined(self.inputs.out_prefix):\n            out_prefix = op.abspath(fname)\n        else:\n            out_prefix = self.inputs.out_prefix\n\n        if ext is None:\n            ext = fext\n\n        return out_prefix + '_' + name + ext\n", "path": "nipype/interfaces/dipy/base.py"}], "after_files": [{"content": "# -*- coding: utf-8 -*-\n\"\"\" Base interfaces for dipy \"\"\"\nimport os.path as op\nimport numpy as np\nfrom nipype.interfaces.base import (traits, File, isdefined,\n                                    BaseInterface, BaseInterfaceInputSpec)\nfrom ... import logging\n\nIFLOGGER = logging.getLogger('interface')\n\nHAVE_DIPY = True\ntry:\n    import dipy\nexcept ImportError:\n    HAVE_DIPY = False\n\n\ndef no_dipy():\n    \"\"\" Check if dipy is available \"\"\"\n    global HAVE_DIPY\n    return not HAVE_DIPY\n\n\ndef dipy_version():\n    \"\"\" Check dipy version \"\"\"\n    if no_dipy():\n        return None\n\n    return dipy.__version__\n\n\nclass DipyBaseInterface(BaseInterface):\n\n    \"\"\"\n    A base interface for py:mod:`dipy` computations\n    \"\"\"\n    def __init__(self, **inputs):\n        if no_dipy():\n            IFLOGGER.warn('dipy was not found')\n            # raise ImportError('dipy was not found')\n        super(DipyBaseInterface, self).__init__(**inputs)\n\n\nclass DipyBaseInterfaceInputSpec(BaseInterfaceInputSpec):\n    in_file = File(exists=True, mandatory=True, desc=('input diffusion data'))\n    in_bval = File(exists=True, mandatory=True, desc=('input b-values table'))\n    in_bvec = File(exists=True, mandatory=True, desc=('input b-vectors table'))\n    b0_thres = traits.Int(700, usedefault=True, desc=('b0 threshold'))\n    out_prefix = traits.Str(desc=('output prefix for file names'))\n\n\nclass DipyDiffusionInterface(DipyBaseInterface):\n\n    \"\"\"\n    A base interface for py:mod:`dipy` computations\n    \"\"\"\n    input_spec = DipyBaseInterfaceInputSpec\n\n    def _get_gradient_table(self):\n        bval = np.loadtxt(self.inputs.in_bval)\n        bvec = np.loadtxt(self.inputs.in_bvec).T\n        from dipy.core.gradients import gradient_table\n        gtab = gradient_table(bval, bvec)\n\n        gtab.b0_threshold = self.inputs.b0_thres\n        return gtab\n\n    def _gen_filename(self, name, ext=None):\n        fname, fext = op.splitext(op.basename(self.inputs.in_file))\n        if fext == '.gz':\n            fname, fext2 = op.splitext(fname)\n            fext = fext2 + fext\n\n        if not isdefined(self.inputs.out_prefix):\n            out_prefix = op.abspath(fname)\n        else:\n            out_prefix = self.inputs.out_prefix\n\n        if ext is None:\n            ext = fext\n\n        return out_prefix + '_' + name + ext\n", "path": "nipype/interfaces/dipy/base.py"}]}