use English '-no_match_vars';
open $input_fh, '<', $input_fn or die 'Could not open file: ', $OS_ERROR;
my $hash;
while ( my $line = <$input_fh> ) {

    chomp $line;
    
    last if ! $line;
    
    # Split line with a limit of two
    my ( $word1 , $word2 ) = split /:/, $line, 2;  
    $hash->{$word1} = $word2;   
}
close $input_fh or die 'Could not close file: $OS_ERROR';