class_docstr: Container for colormaps that are known to Matplotlib by name.
  
  The universal registry instance is `matplotlib.colormaps`. There should be
  no need for users to instantiate `.ColormapRegistry` themselves.
  
  Read access uses a dict-like interface mapping names to `.Colormap`\s::
  
      import matplotlib as mpl
      cmap = mpl.colormaps['viridis']
  
  Returned `.Colormap`\s are copies, so that their modification does not
  change the global definition of the colormap.
  
  Additional colormaps can be added via `.ColormapRegistry.register`::
  
      mpl.colormaps.register(my_colormap)
  
  To get a list of all registered colormaps, you can do::
  
      from matplotlib import colormaps
      list(colormaps)
code: def __getitem__(self, item):
      try:
          return self._cmaps[item].copy()
      except KeyError:
          raise KeyError(
              f"{item!r} is not a known colormap name"
          ) from None
  
imports: from collections.abc import Mapping
  import functools
  import numpy
  from numpy import ma
  import matplotlib
  from matplotlib import _api, colors, cbook, scale
  from matplotlib._cm import datad
  from matplotlib._cm_listed import cmaps
label_desc: Use image node_id 2 for calling the ColormapRegistry obj's underlying member method code with example usage: obj.__getitem__(item) and returns: self