code: def slice(self, start=None, stop=None, step=None):
          
          check_type(start, int)
          check_type(stop, int)
          check_type(step, int)
  
          if step is not None and step < 0:
              raise ValueError('Only positive steps are currently supported')
  
          return _series_str_result(self, weld_str_slice, start=start, stop=stop, step=step)
docs: Slice substrings from each element.
  
          Note that negative step is currently not supported.
  
          Parameters
          ----------
          start : int
          stop : int
          step : int
  
          Returns
          -------
          Series