code: def lookup(self, c, lookup_order="CF"):
          
          if not isinstance(c, six.text_type):
              raise TypeError(u"Character to lookup must be of type 'unicode'!")
          for d in lookup_order:
              try:
                  return self._casefold_map[d][c]
              except KeyError:
                  pass
          return c
docs: Function to lookup a character in the casefold map.
  
          The casefold map has four sub-tables, the 'C' or common table, the 'F' or
          full table, the 'S' or simple table and the 'T' or the Turkic special
          case table.  These tables correspond to the statuses defined in the
          CaseFolding.txt file.  We can specify the order of the tables to use for
          performing the lookup by the lookup_order parameter.
  
          Per the usage specified in the CaseFolding.txt file, we can use the 'C'
          and 'S' tables for doing a simple case fold.  To perform a full case
          fold, we can use the 'C' and 'F' tables.  The default behavior for this
          function is a full case fold (lookup_order="CF").
  
          :param c: character to lookup
          :param lookup_order: