# Change this: sub add_two_numbers_which_might_be_undef { $_[0] + $_[1]; } # To one of these (depending on perl version): # 1 sub add_two_numbers_which_might_be_undef { # See 'perldoc perllexwarn' for all the categories of warnings # because its better to only disable the warnings you're expecting no warnings "uninitialized"; $_[0] + $_[1]; } # 2 sub add_two_numbers_which_might_be_undef { local $^W; $_[0] + $_[1]; }