code: def add_parameter(self, name, value=None):
  		
  		if name not in self.__query:
  			self.__query[name] = [value]
  		else:
  			self.__query[name].append(value)
docs: 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