Add new parameter value to this query. New value will be appended to previously added values.

		:param name: parameter name
		:param value: value to add (None to set null-value)
		:return: None

def add_parameter(self, name, value=None):
		""" Add new parameter value to this query. New value will be appended to previously added values.

		:param name: parameter name
		:param value: value to add (None to set null-value)
		:return: None
		"""
		if name not in self.__query:
			self.__query[name] = [value]
		else:
			self.__query[name].append(value)