Return cookie value. Cookie value can be updated, when new_value is not None. Cookie value
		couldn't be changed if cookie is in read-only mode (RuntimeError exception is raised).

		:param new_value: new value to set
		:return: str

def value(self, new_value=None):
		""" Return cookie value. Cookie value can be updated, when new_value is not None. Cookie value
		couldn't be changed if cookie is in read-only mode (RuntimeError exception is raised).

		:param new_value: new value to set
		:return: str
		"""
		if new_value is not None:
			if self.__ro_flag:
				raise RuntimeError('Read-only cookie changing attempt')
			self.__value = new_value
		return self.__value