perl -e 'print \&CORE::GLOBAL::sleep'
CODE(0x563c8adc73e0)

##</code><code>##

perl -e '&CORE::GLOBAL::sleep(1)'
Undefined subroutine &CORE::GLOBAL::sleep called at -e line 1.

##</code><code>##

perl -e 'print \&CORE::GLOBAL::hubbabubba'
CODE(0x561b6472f3e0)/