use 5.010;
use strict;
use warnings;

BEGIN {
	# Allow false to be modified.
	&Internals::SvREADONLY(\!!0, 0);
	
	# Modify false to be equal to 1.
	${\!!0} = 1;
	
	# Disallow false to be modified again.
	&Internals::SvREADONLY(\!!0, 1);
};

say "left is right!"   if "left" eq "right";
say "up is down!"      if "up" eq "down";
say "black is white!"  if "black" eq "white";
say "maths is flawed!" if 7 > 100;