Handle /unapi set of pages.

def index():
    """Handle /unapi set of pages."""
    # Prepare mappings from configuration.
    mapping = cfg['UNAPI_FORMAT_MAPPING']
    names = {mapping[k]: k for k in mapping}
    # Clean request arguments.
    identifier = request.values.get('id', type=int)
    format_ = request.values.get('format')
    format_ = mapping.get(format_, format_)
    # Redirect to correct record format.
    if identifier and format_:
        return redirect(url_for('record.metadata', recid=identifier,
                                of=format_))

    formats = [{
        'name': names[of],
        'type': values['content_type'],
        'docs': values.get('url'),
    } for of, values in iteritems(output_formats) if of in names]

    response = make_response(render_template(
        'unapi/index.xml', identifier=identifier, formats=formats))
    response.headers['Content-Type'] = 'application/xml'
    return response