code: def validate_cycler(s):
      "return a Cycler object from a string repr or the object itself"
      if isinstance(s, six.string_types):
          try:
              # 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:
              # http://nedbatchelder.com/blog/201206/eval_really_is_dangerous.html
              # We should replace this eval with a combo of PyParsing and
              # ast.literal_eval()
              if ".__" in s.replace(" ", ""):
                  raise ValueError(
                      "'%s' seems to have dunder methods. Raising"
                      " an exception for your safety"
                  )
              s = eval(s, {"cycler": cycler, "__builtins__": {}})
          except BaseException as e:
              raise ValueError(
                  "'%s' is not a valid cycler construction: %s" % (s, e)
              )
      # Should make sure what comes from the above eval()
      # is a Cycler object.
      if isinstance(s, Cycler):
          cycler_inst = s
      else:
          raise ValueError(
              "object was not a string or Cycler instance: %s" % s
          )
  
      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(
                  "Cannot specify both '{0}' and alias '{1}'"
                  " in the same prop_cycle".format(norm_prop, prop)
              )
          if norm_prop in checker:
              raise ValueError(
                  "Another property was already aliased to '{0}'."
                  " Collision normalizing '{1}'.".format(
                      norm_prop, prop
                  )
              )
          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: 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 38 for calling a global function with example usage: validate_cycler(s) and returns: cycler_inst