Strings are handled a bit differently by the Zend engine
than other values such as integers, Booleans, etc., which don't require
additional memory allocation for storing their values. If you want to
return a string from a function, introduce a new string variable to the symbol
table, or do something similar, you have to make sure that the memory the
string will be occupying has previously been allocated, using the
aforementioned e*() functions for allocation. (This might
not make much sense to you yet; just keep it somewhere in your head for now - we'll get
back to it shortly.)
