function onElement( i, el ) {
			var d = $( el ).attr( 'href' ).slice( '/package/'.length );
			if ( d !== opts.pkg && cache[ d ] === void 0 ) {
				cache[ d ] = true;
			}
		}
Callback invoked on finding a package link.

@private
@param {NonNegativeInteger} i - index
@param {Element} el - element