code: def select_default(self):
          
          if self._default is None:
              if not self._set_option_by_index(0):
                  utils.error_format(self.description + "\n" +
                  "Unable to select default option as the Combo is empty")
  
          else:
              if not self._set_option(self._default):
                  utils.error_format( self.description + "\n" +
                  "Unable to select default option as it doesnt exist in the Combo")
docs: Resets the combo box to the original "selected" value from the
          constructor (or the first value if no selected value was specified).