This function uses a backtrace generated from debug_backtrace
and so will not work at all in PHP < 4.3.0. The frame should reference the frame that
contains the source of the error.
Parameter
array
$code
Results of debug_backtrace()
unused
$params
integer
$backtrace
backtrace frame.
Return value
returns either
array('file' => file, 'line' => line,
'function' => function name, 'class' => class name) or
if this doesn't work, then false
