my $output = "phones_out.txt";
open(OUT,"+>$output");
my $PHONE_FILE = $ARGV[0] || 'phones.txt';
my @COLOURS = <DATA>;
my $GET_MODEL = qr{\A ( [^\n]+ ) }x;

open my $PHONES, '<', $PHONE_FILE or die "Cannot open $PHONE_FILE\n";
Case Cover";
while (my ($phn) = <$PHONES> =~ $GET_MODEL)

{
Do something (matches phone models to colours)

}