code: def default_heatmap():
      import matplotlib.pyplot as plt
  
      return truncate_colormap(plt.cm.OrRd, 0.1, 0.7)
  
imports: from copy import copy
  from inspect import signature, _empty
  import re
  from collections.abc import Iterable
  from collections import defaultdict
  from itertools import product
  from six import string_types
label_desc: Use image node_id 15 for calling a global function with example usage: default_heatmap() and returns: truncate_colormap