perldebguts - Guts of Perl debugging
This is not the perldebug(1) manpage, which tells you how to use the debugger. This manpage
describes low-level details concerning the debugger's internals, which range from difficult to
impossible to understand for anyone who isn't incredibly intimate with Perl's guts. Caveat
perldebug, perlguts, perlrun re, and Devel::DProf.