text: from django.db.models import BooleanField
  
  
  class StrengthField(BooleanField):
      """Represents a WordFeature's strength for a Category."""
      STRENGTHS = [(True, 'strong'), (False, 'weak')]
  
      def __init__(self, **kwargs):
          """
          Constructor for the Field.
          :param **kwargs: arguments for the constructor.
          :return:
          """
          kwargs['choices'] = StrengthField.STRENGTHS
          BooleanField.__init__(
              self, **kwargs)
  
      def strong(self):
          """
          Determines whether the Strength field is strong or not.
          :return: True if the Strength field is strong
          """
          return self.value
  
      def weak(self):
          """
          Determines whether the Strength field is weak or not.
          :return: True if the Strength field is strong
          """
          return not self.value
  