code: def validate_cycler(s):
      """Return a Cycler object from a string repr or the object itself."""
      if isinstance(s, str):
          # TODO: We might want to rethink this...
          # While I think I have it quite locked down, it is execution of
          # arbitrary code without sanitation.
          # Combine this with the possibility that rcparams might come from the
          # internet (future plans), this could be downright dangerous.
          # I locked it down by only having the 'cycler()' function available.
          # UPDATE: Partly plugging a security hole.
          # I really should have read this:
          # https://nedbatchelder.com/blog/201206/eval_really_is_dangerous.html
          # We should replace this eval with a combo of PyParsing and
          # ast.literal_eval()
          try:
              _DunderChecker().visit(ast.parse(s))
              s = eval(s, {"cycler": cycler, "__builtins__": {}})
          except BaseException as e:
              raise ValueError(
                  f"{s!r} is not a valid cycler construction: {e}"
              ) from e
      # Should make sure what comes from the above eval()
      # is a Cycler object.
      if isinstance(s, Cycler):
          cycler_inst = s
      else:
          raise ValueError(
              f"Object is not a string or Cycler instance: {s!r}"
          )
  
      unknowns = cycler_inst.keys - (
          set(_prop_validators) | set(_prop_aliases)
      )
      if unknowns:
          raise ValueError("Unknown artist properties: %s" % unknowns)
  
      # Not a full validation, but it'll at least normalize property names
      # A fuller validation would require v0.10 of cycler.
      checker = set()
      for prop in cycler_inst.keys:
          norm_prop = _prop_aliases.get(prop, prop)
          if norm_prop != prop and norm_prop in cycler_inst.keys:
              raise ValueError(
                  f"Cannot specify both {norm_prop!r} and alias "
                  f"{prop!r} in the same prop_cycle"
              )
          if norm_prop in checker:
              raise ValueError(
                  f"Another property was already aliased to "
                  f"{norm_prop!r}. Collision normalizing {prop!r}."
              )
          checker.update([norm_prop])
  
      # This is just an extra-careful check, just in case there is some
      # edge-case I haven't thought of.
      assert len(checker) == len(cycler_inst.keys)
  
      # Now, it should be safe to mutate this cycler
      for prop in cycler_inst.keys:
          norm_prop = _prop_aliases.get(prop, prop)
          cycler_inst.change_key(prop, norm_prop)
  
      for key, vals in cycler_inst.by_key().items():
          _prop_validators[key](vals)
  
      return cycler_inst
  
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 39 for calling a global function with example usage: validate_cycler(s) and returns: cycler_inst