code: def deselect_by_value(self, value):
          
          if not self.is_multiple:
              raise NotImplementedError("You may only deselect options of a multi-select")
          matched = False
          css = "option[value = %s]" % self._escapeString(value)
          opts = self._el.find_elements(By.CSS_SELECTOR, css)
          for opt in opts:
              self._unsetSelected(opt)
              matched = True
          if not matched:
              raise NoSuchElementException("Could not locate element with value: %s" % value)
docs: Deselect all options that have a value matching the argument. That is, when given "foo" this
             would deselect an option like:
  
              <option value="foo">Bar</option>
  
             :Args:
              - value - The value to match against
  
              throws NoSuchElementException If there is no option with specified value in SELECT