gistfile1.js

    map: function(object, fn) {
        var rv = '' ;

        // enumerate keys so that we can tell first and last
        var keys = [] ;
        for (k in object) keys[keys.length] = k ;

        // invoke the block with each key/value pair (and first/last)
        for (var i = 0 ; i < keys.length ; i++) {
            rv += fn({
                k: keys[i],
                v: object[keys[i]],
                first: 0 == i,
                last: (keys.length - 1 == i)
            }) ;
        }

        return rv ;
    },

/* ...

<a href='#!{{href}}'{{#id}} id='{{.}}'{{/id}}{{#class}} class='{{.}}'{{/class}}{{#style}} style='{{.}}'{{/style}} {{#map data}}data-{{k}}='{{v}}'{{^last}} {{/last}}{{/map}}>{{content}}</a>

... */