package MyFirstModul;
use strict;

sub new{
    my $pkg  = shift;
    my $self = {};
    bless $self, ref $pkg || $pkg;
    return $self;      
}

sub replace{
    my $self = shift;
    my $data = shift;
    $data =~ s/a/b/gi;
    return $data;    
}

1;