use IO::Prompt;

my $query_prompt="$username would like to align your protein sequences globally or locally? (enter either 'g' or 'l')";
my $error_prompt="$username, your selection was incomprehensible (enter either 'g' or 'l'):";

my $alignment_type = prompt ( -prompt => $query_prompt,
                              -require => { $error_prompt => qr/^[gl]$/i },
                            );