code: def groupsValidator(value):
      """
      Check the validity of the groups.
      Version 3+ (though it's backwards compatible with UFO 1 and UFO 2).
  
      >>> groups = {"A" : ["A", "A"], "A2" : ["A"]}
      >>> groupsValidator(groups)
      (True, None)
  
      >>> groups = {"" : ["A"]}
      >>> valid, msg = groupsValidator(groups)
      >>> valid
      False
      >>> print(msg)
      A group has an empty name.
  
      >>> groups = {"public.awesome" : ["A"]}
      >>> groupsValidator(groups)
      (True, None)
  
      >>> groups = {"public.kern1." : ["A"]}
      >>> valid, msg = groupsValidator(groups)
      >>> valid
      False
      >>> print(msg)
      The group data contains a kerning group with an incomplete name.
      >>> groups = {"public.kern2." : ["A"]}
      >>> valid, msg = groupsValidator(groups)
      >>> valid
      False
      >>> print(msg)
      The group data contains a kerning group with an incomplete name.
  
      >>> groups = {"public.kern1.A" : ["A"], "public.kern2.A" : ["A"]}
      >>> groupsValidator(groups)
      (True, None)
  
      >>> groups = {"public.kern1.A1" : ["A"], "public.kern1.A2" : ["A"]}
      >>> valid, msg = groupsValidator(groups)
      >>> valid
      False
      >>> print(msg)
      The glyph "A" occurs in too many kerning groups.
      """
      bogusFormatMessage = (
          "The group data is not in the correct format."
      )
      if not isDictEnough(value):
          return False, bogusFormatMessage
      firstSideMapping = {}
      secondSideMapping = {}
      for groupName, glyphList in value.items():
          if not isinstance(groupName, (str)):
              return False, bogusFormatMessage
          if not isinstance(glyphList, (list, tuple)):
              return False, bogusFormatMessage
          if not groupName:
              return False, "A group has an empty name."
          if groupName.startswith("public."):
              if not groupName.startswith(
                  "public.kern1."
              ) and not groupName.startswith("public.kern2."):
                  # unknown public.* name. silently skip.
                  continue
              else:
                  if len("public.kernN.") == len(groupName):
                      return (
                          False,
                          "The group data contains a kerning group with an incomplete name.",
                      )
              if groupName.startswith("public.kern1."):
                  d = firstSideMapping
              else:
                  d = secondSideMapping
              for glyphName in glyphList:
                  if not isinstance(glyphName, str):
                      return (
                          False,
                          "The group data %s contains an invalid member."
                          % groupName,
                      )
                  if glyphName in d:
                      return (
                          False,
                          'The glyph "%s" occurs in too many kerning groups.'
                          % glyphName,
                      )
                  d[glyphName] = groupName
      return True, None
  
imports: import calendar
  from io import open
  import fs.base
  import fs.osfs
  from collections.abc import Mapping
  from fontTools.ufoLib.utils import numberTypes
label_desc: Use image node_id 43 for calling a global function with example usage: groupsValidator(value) and returns: True,  None, False,  bogusFormatMessage, False,  bogusFormatMessage, False,  bogusFormatMessage, False,  str, False,  str, False,  unknown, False,  unknown