$ splain
/Users/ken/perl5/perlbrew/perls/perl-5.18.0t/bin/splain: Reading from STDIN
Global symbol "$x" requires explicit package name
Global symbol "$x" requires explicit package name (#1)
    (F) You've said "use strict" or "use strict vars", which indicates 
    that all variables must either be lexically scoped (using "my" or "state"), 
    declared beforehand using "our", or explicitly qualified to say 
    which package the global variable is in (using "::").
    
^C