# perl -wle 'sub aaa{print 1}; exists &main::aaa and print "yes"'
yes
# perl -wle 'sub aaa{print 1}; exists &main::aab and print "yes"'
#


-- 
David L Nicol
"For every thousand hacking away
at the leaves of evil, there is one
striking at the root." -- Thoreau.