I'm a front end person who is doing more and more php.
Also I'm used to javascript where I use a callback to make sure a function has completed before using the results of that function.

Recently I was in a situation with PHP where line 10 uses the results of a function and assigns them to a variable.
Line 11 then uses that variable, there is no check to see if the function has completed.
My instinct was to change it to include a callback.
But someone told me that php is a sequential language and that every line is evaluated before moving to the next. Is this true?