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)
docstr: Remove a colormap from the registry.
  
  You cannot remove built-in colormaps.
  
  If the named colormap is not registered, returns with no error, raises
  if you try to de-register a default colormap.
  
  .. warning::
  
      Colormap names are currently a shared namespace that may be used
      by multiple packages. Use `unregister` only if you know you
      have registered that name before. In particular, do not
      unregister just in case to clean the name before registering a
      new colormap.
  
  Parameters
  ----------
  name : str
      The name of the colormap to be removed.
  
  Raises
  ------
  ValueError
      If you try to remove a default built-in colormap.
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code: def unregister(self, name):
      """
      Remove a colormap from the registry.
  
      You cannot remove built-in colormaps.
  
      If the named colormap is not registered, returns with no error, raises
      if you try to de-register a default colormap.
  
      .. warning::
  
          Colormap names are currently a shared namespace that may be used
          by multiple packages. Use `unregister` only if you know you
          have registered that name before. In particular, do not
          unregister just in case to clean the name before registering a
          new colormap.
  
      Parameters
      ----------
      name : str
          The name of the colormap to be removed.
  
      Raises
      ------
      ValueError
          If you try to remove a default built-in colormap.
      """
      if name in self._builtin_cmaps:
          raise ValueError(
              f"cannot unregister {name!r} which is a builtin "
              "colormap."
          )
      self._cmaps.pop(name, 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 8 for calling the ColormapRegistry obj's underlying member method code with example usage: obj.unregister(name) without return types