text: """
  Term similarity classes provide similarity values for a pair of terms.
  """
  
  
  class TermSimilarity():
      """
      Term similarity classes should inherit from this class
      """
  
      def __getitem__(self, terms):
          """
          Args:
              - terms -> a 2-tuple of strings
  
          Returns: a scalar value
          """
          raise NotImplementedError
  
  
  from .wikipedia import WikipediaSimilarity
  