docs: def text_to_data(self, text, elt, ps):
          '''convert text into typecode specific data.
          '''
          v = text
          if v == 'false': 
              if self.pyclass is None:
                  return False
              return self.pyclass(False)
  
          if v == 'true': 
              if self.pyclass is None:
                  return True
              return self.pyclass(True)
  
          try:
              v = int(v)
          except:
              try:
                  v = long(v)
              except:
                  raise EvaluateException('Unparseable boolean', 
                          ps.Backtrace(elt))
  
          if v:
              if self.pyclass is None:
                  return True
              return self.pyclass(True)
  
          if self.pyclass is None:
               return False
          return self.pyclass(False)