You don't have to stash a reference to a sub in order to call it. I don't really know what you are trying to do. Please provide a minimal example showing what you tried similar to the following code and tell us what doesn't work

use strict;
use warnings;

use CGI qw/:standard/;

sub header {
    return "this is not the header you are looking for\n";
}

print header;

print CGI::header;
print main::header;
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