new_contents: from werkzeug.routing import ValidationError, UnicodeConverter
  from sqlalchemy_utils import get_class_by_table
  
  from app.models import Word
  
  
  class WordClassConverter(UnicodeConverter):
      """ Converts a word class string into a class. """
      def to_python(self, value):
          try:
              word_class = get_class_by_table(Word, Word.__table__, data={"type": value})
              return word_class
          except ValueError:
              raise ValidationError()
subject: Add word class converter