code: def validate_ps_distiller(s):
      if isinstance(s, str):
          s = s.lower()
      if s in ("none", None, "false", False):
          return None
      else:
          return ValidateInStrings(
              "ps.usedistiller", ["ghostscript", "xpdf"]
          )(s)
  
imports: import ast
  from functools import lru_cache, reduce
  from numbers import Real
  import operator
  import os
  import re
  import numpy
  from matplotlib import _api, cbook
  from matplotlib.cbook import ls_mapper
  from matplotlib.colors import Colormap, is_color_like
  from matplotlib._fontconfig_pattern import parse_fontconfig_pattern
  from matplotlib._enums import JoinStyle, CapStyle
  from cycler import Cycler, cycler
label_desc: Use image node_id 26 for calling a global function with example usage: validate_ps_distiller(s) and returns: None, ValidateInStrings