code: def enforce_type(self, attr, val):
          
          if not attr in self.types:
              return utfstr(val)
          elif self.types[attr] == 'int':
              return int(float(val))
          elif self.types[attr] == 'float':
              return float(val)
          else:
              return utfstr(val)
docs: converts a value to the attribute's type