docs: def pattern(self, value):
          """
          Setter for **self.__pattern** attribute.
  
          :param value: Attribute value.
          :type value: unicode
          """
  
          if value is not None:
              assert type(value) in (unicode, QString), \
                  "'{0}' attribute: '{1}' type is not 'unicode' or 'QString'!".format("pattern", value)
          self.__pattern = value