sub parse {
    my $self = shift;
    my @opts = @_;
    my %opts;
    if ( ! @opts || scalar @opts % 2 ) {
        $self->COMPLAIN("bad number of arguments.");
        return;
    }
    else {
        %opts = @opts;
        if ( ! $opts{-format} || ! grep(ucfirst($opts{-format}), @parsers) ) {
            $self->COMPLAIN("no valid format specified.");
            return;
        }
        if ( $opts{-file} && ( ! -T $opts{-file} || ! -r $opts{-file} ) ) {
            $self->COMPLAIN("file not found, not a text file, or not readable");
            return;
        }
        elsif ( ! $opts{-file} && ! $opts{-string} ) {
            $self->COMPLAIN("no data source specified.");
            return;
        }
        my $lib = ref $self;
        $lib .= '::' . ucfirst($opts{-format});
        eval "require $lib";
        my $parser = new $lib;
        if ( $opts{-file} && $parser->can('from_handle') ) {
            open(FH, $opts{-file});
            $opts{-handle} = \*FH;
            return $parser->from_handle(%opts);
        }
        if ( $opts{-string} && $parser->can('from_string') ) {
            return $parser->from_string(%opts);
        }
        $self->COMPLAIN("the parser can't handle the data source specified");
        return;
    }
}