Waiting For An App42 Function To Finish In Unity

Question

This may be a simple question, but I was wondering if there's a way to wait for a function to finish successfully (or unsuccessfully) complete before moving on to the next line of code. 

For instance, in psuedocode, I want to do something like:

 

yield createuser(parameters);

do stuff

 

However, when I'm using these functions, it'll go from createuser to 'do stuff' before createuser is finished.  I chain functions within the callbacks right now, but I feel that's messy.  Any suggestions?