Try the manual entry.
[quote:26dg0304]Returning values from functions
Functions can also return a result. For example, a factorial function could calculate the mathematical result and return it. In an On function event, the return value can be set using the Set return value action.
If the event was called using the Call function action, the returned value is afterwards available using the ReturnValue expression. Functions can also be called directly from an expression using the Call expression; in this case the return value is automatically returned as the result of the Call expression.
And in case you are not familiar with what an expression is: https://www.scirra.com/manual/78/expressions