code: def validate_float_or_None(s):
      """convert s to float, None or raise"""
      # values directly from the rc file can only be strings,
      # so we need to recognize the string "None" and convert
      # it into the object. We will be case-sensitive here to
      # avoid confusion between string values of 'none', which
      # can be a valid string value for some other parameters.
      if s is None or s == "None":
          return None
      try:
          return float(s)
      except ValueError:
          raise ValueError(
              'Could not convert "%s" to float or None' % s
          )
  
imports: from __future__ import absolute_import, division, print_function
  import six
  from functools import reduce
  import operator
  import os
  import warnings
  import re
  from matplotlib import cbook, testing
  from matplotlib.cbook import mplDeprecation, deprecated, ls_mapper
  from matplotlib.fontconfig_pattern import parse_fontconfig_pattern
  from matplotlib.colors import is_color_like
  from cycler import Cycler, cycler
label_desc: Use image node_id 8 for calling a global function with example usage: validate_float_or_None(s) and returns: None, float