def addService(self, moduleName, serviceName, service):
serviceIdentifier = "<STR_LIT>".format(moduleName, serviceName)<EOL>if serviceIdentifier not in self._services:<EOL><INDENT>self._services[serviceIdentifier] = service<EOL><DEDENT>else:<EOL><INDENT>message = "<STR_LIT>""<STR_LIT>".format(serviceIdentifier)<EOL>raise Exception(message)<EOL><DEDENT>
Add a service instance to the application service pool.

:param moduleName: <str> module name in which the service is located
:param serviceName: <str> service name
:param service: <object> service instance
:return: <void>