The returned array contains an array of arrays.
Each array appears to contain:
 = function name
 = filename that contains function
 = *calling* line number in *calling* file
 = An array which is usually empty
(PECL apd 0.2-0.4)
apd_callstack — Returns the current call stack as an array
Returns the current call stack as an array
An array containing the current call stack.
Example #1 apd_callstack() example