package My::Module;

our $fh;

sub import {
    shift;              # throw away my own package name
    $fh   = shift;
    if ( not -w $fh )   # check to see it's a good filehandle
       { die 'Bad filehandle in use My::Module' };
}

sub later {
    print $fh 'Arbitrary text.';
}

1;