sub scanfile {
    croak "Usage: scanfile(\$filename)"
      unless  1 == @ARGV;
    my $data= do {
        my $filename= shift;
        require 5.6;  # Autovivification of file handle:
        open my $handle, '<', $filename
          or  croak "Can't read file [$filename], $!";
        local $/;
        <$handle>;
    };
    return scan( $data );
}