#!/usr/bin/perl --
use strict; use warnings;

Main( @ARGV );
exit( 0 );

sub Main {
    @_ or die "\nUsage: $0 infile infile infile > outfile\n";

    my @files = map { open my( $fh ), '<', $_ or die $^E; $fh; } @_;

    while( my @ofh = grep not eof, @files ) {
        print getOne( shift @ofh ) while @ofh;
    }
} ## end sub Main

sub getOne {
    ...;
}

## perltidy -olq  -csc -csci=10 -cscl="sub : BEGIN END" -otr -opr -ce -nibc -i=4 -pt=0   "-nsak=*"