code: def validate_read_preference_tags(name, value):
      
      if not isinstance(value, list):
          value = [value]
  
      tag_sets = []
      for tag_set in value:
          if tag_set == '':
              tag_sets.append({})
              continue
          try:
              tag_sets.append(dict([tag.split(":")
                                    for tag in tag_set.split(",")]))
          except Exception:
              raise ValueError("%r not a valid "
                               "value for %s" % (tag_set, name))
      return tag_sets
docs: Parse readPreferenceTags if passed as a client kwarg.