code: def _validate_flavor(flavor):
      if flavor is None:
          flavor = "lxml", "bs4"
      elif isinstance(flavor, string_types):
          flavor = (flavor,)
      elif isinstance(flavor, compat.Iterable):
          if not all(isinstance(flav, string_types) for flav in flavor):
              raise TypeError(
                  "Object of type {typ!r} is not an iterable of "
                  "strings".format(typ=type(flavor).__name__)
              )
      else:
          fmt = (
              "{flavor!r}"
              if isinstance(flavor, string_types)
              else "{flavor}"
          )
          fmt += " is not a valid flavor"
          raise ValueError(fmt.format(flavor=flavor))
  
      flavor = tuple(flavor)
      valid_flavors = set(_valid_parsers)
      flavor_set = set(flavor)
  
      if not flavor_set & valid_flavors:
          raise ValueError(
              "{invalid} is not a valid set of flavors, valid "
              "flavors are {valid}".format(
                  invalid=_print_as_set(flavor_set),
                  valid=_print_as_set(valid_flavors),
              )
          )
      return flavor
  
imports: from distutils.version import LooseVersion
  import numbers
  import os
  import re
  import pandas.compat
  from pandas.compat import binary_type, iteritems, lmap, lrange, raise_with_traceback, string_types, u
  from pandas.errors import AbstractMethodError, EmptyDataError
  from pandas.core.dtypes.common import is_list_like
  from pandas import Series
  from pandas.io.common import _is_url, _validate_header_arg, urlopen
  from pandas.io.formats.printing import pprint_thing
  from pandas.io.parsers import TextParser
label_desc: Use image node_id 10 for calling a global function with example usage: _validate_flavor(flavor) and returns: flavor