code: def validate_hatch(s):
      """
      Validate a hatch pattern.
      A hatch pattern string can have any sequence of the following
      characters: ``\\ / | - + * . x o O``.
  
      """
      if not isinstance(s, six.string_types):
          raise ValueError("Hatch pattern must be a string")
      unknown = set(s) - {
          "\\",
          "/",
          "|",
          "-",
          "+",
          "*",
          ".",
          "x",
          "o",
          "O",
      }
      if unknown:
          raise ValueError(
              "Unknown hatch symbol(s): %s" % list(unknown)
          )
      return 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 36 for calling a global function with example usage: validate_hatch(s) and returns: s