class_docstr: Series/Frames plotting accessor and method.
  
  Uses the backend specified by the
  option ``plotting.backend``. By default, plotly is used.
  
  Plotting methods can also be accessed by calling the accessor as a method
  with the ``kind`` argument:
  ``s.plot(kind='hist')`` is equivalent to ``s.plot.hist()``
code: def _get_plot_backend(backend=None):
      backend = backend or get_option("plotting.backend")
      # Shortcut
      if backend in PandasOnSparkPlotAccessor._backends:
          return PandasOnSparkPlotAccessor._backends[backend]
  
      if backend == "matplotlib":
          # Because matplotlib is an optional dependency,
          # we need to attempt an import here to raise an ImportError if needed.
          try:
              # test if matplotlib can be imported
              import matplotlib  # noqa: F401
              from pyspark.pandas.plot import matplotlib as module
          except ImportError:
              raise ImportError(
                  "matplotlib is required for plotting when the "
                  "default backend 'matplotlib' is selected."
              ) from None
  
          PandasOnSparkPlotAccessor._backends["matplotlib"] = module
      elif backend == "plotly":
          try:
              # test if plotly can be imported
              import plotly  # noqa: F401
              from pyspark.pandas.plot import plotly as module
          except ImportError:
              raise ImportError(
                  "plotly is required for plotting when the "
                  "default backend 'plotly' is selected."
              ) from None
  
          PandasOnSparkPlotAccessor._backends["plotly"] = module
      else:
          module = PandasOnSparkPlotAccessor._find_backend(backend)
          PandasOnSparkPlotAccessor._backends[backend] = module
      return module
  
imports: import importlib
  import pandas
  import numpy
  from pandas.core.base import PandasObject
  from pandas.core.dtypes.inference import is_integer
  from pyspark.ml.feature import Bucketizer
  from pyspark.mllib.stat import KernelDensity
  from pyspark.sql import functions
  from pyspark.pandas.missing import unsupported_function
  from pyspark.pandas.config import get_option
  from pyspark.pandas.utils import name_like_string
label_desc: Use image node_id 3 for calling the PandasOnSparkPlotAccessor obj's underlying member method code with example usage: obj._get_plot_backend(backend) and returns: module, PandasOnSparkPlotAccessor