code: def update(self, value=None):
          'Updates the ProgressBar to a new value.'
  
          if value is not None and value is not UnknownLength:
              if (self.maxval is not UnknownLength
                  and not 0 <= value <= self.maxval):
  
                  raise ValueError('Value out of range')
  
              self.currval = value
  
  
          if not self._need_update(): return
          if self.start_time is None:
              raise RuntimeError('You must call "start" before calling "update"')
  
          now = time.time()
          self.seconds_elapsed = now - self.start_time
          self.next_update = self.currval + self.update_interval
          self.fd.write(self._format_line() + '\r')
          self.last_update_time = nof update(self, value=None):
          'Updates the ProgressBar to a new value.'
  
          if value is not None and value is not UnknownLength:
              if (self.maxval is not UnknownLength
                  and not 0 <= value <= self.maxval):
  
                  raise ValueError('Value out of range')
  
              self.currval = value
  
  
          if not self._need_update(): return
          if self.start_time is None:
              raise RuntimeError('You must call "start" before calling "update"')
  
          now = time.time()
          self.seconds_elapsed = now - self.start_time
          self.next_update = self.currval + self.update_interval
          self.fd.write(self._format_line() + '\r')
          self.last_update_time = now
docs: Updates the ProgressBar to a new value.