code: def set_wtscl(self, chip, wtscl_par):
          
          sci_chip = self._image[self.scienceExt,chip]
  
          exptime = 1 #sci_chip._exptime
          _parval = 'unity'
          if wtscl_par is not None:
              if type(wtscl_par) == type(''):
                  if not wtscl_par.isdigit():
                      # String passed in as value, check for 'exptime' or 'expsq'
                      _wtscl_float = None
                      try:
                          _wtscl_float = float(wtscl_par)
                      except ValueError:
                          _wtscl_float = None
                      if _wtscl_float is not None:
                          _wtscl = _wtscl_float
                      elif wtscl_par == 'expsq':
                          _wtscl = exptime*exptime
                          _parval = 'expsq'
                      else:
                          # Default to the case of 'exptime', if
                          #   not explicitly specified as 'expsq'
                          _wtscl = exptime
                  else:
                      # int value passed in as a string, convert to float
                      _wtscl = float(wtscl_par)
              else:
                  # We have a non-string value passed in...
                  _wtscl = float(wtscl_par)
          else:
              # Default case: wt_scl = exptime
              _wtscl = exptime
  
          sci_chip._wtscl_par = _parval
          sci_chip._wtscl = _wtscl
docs: Sets the value of the wt_scl parameter as needed for drizzling.