code: def to_python(self, value):
          
          if not value:
              value = []
  
          # If a list is set then validated its items
          if isinstance(value, list):
              py_list = self.validate_list(value)
          else:  # try to de-serialize value and expect list and then validate
              try:
                  py_list = json.loads(value)
  
                  if not isinstance(py_list, list):
                      raise TypeError
  
                  self.validate_list(py_list)
              except (ValueError, TypeError):
                  raise ValidationError(u'Must be a valid list of strings.')
  
          return py_list
docs: Converts the value into a list.