class_docstr: This is a mixin class to support scalar -> RGBA mapping.  Handles
  normalization and colormapping
docstr: set the normalization instance
docstr_tok: ["set","the","normalization","instance"]
code: def set_norm(self, norm):
      "set the normalization instance"
      if norm is None:
          norm = colors.Normalize()
      self.norm = norm
      self.changed()
  
imports: import numpy
  from numpy import ma
  import matplotlib
  import matplotlib.colors
  import matplotlib.cbook
  from matplotlib._cm import *
label_desc: Use image node_id 10 for calling the ScalarMappable obj's underlying member method code with example usage: obj.set_norm(norm) without return types