twisted.internet.defer.succeed(result) function documentation

Return a Deferred that has already had .callback(result) called.

This is useful when you're writing synchronous code to an asynchronous interface: i.e., some code is calling you expecting a Deferred result, but you don't actually need to do anything asynchronous. Just return defer.succeed(theResult).

See fail for a version of this function that uses a failing Deferred rather than a successful one.