They get used quite often in production code quite often too: any time you have a synchronous implementation to an asynchronous interface. E.g. your DNS name re

They get used quite often in production code quite often too: any time you have a synchronous implementation to an asynchronous interface. E.g. your DNS name resoltion thing may have to go query a Postgres database far away (that'd be asynchronous), but maybe it has to grab an entry from a (Python) list (that'd be synchronous).