index.js

var CLASSES = {
    info:'info',
    tip:'success',
    danger:'danger',
    working:'warning'
};

function makeIcon(name) {
    return '<i class="fa fa-'+name+'" style=""></i>';
}
var ICONS = {
    info: makeIcon('info-circle'),
    tip: makeIcon('mortar-board'), // Diploma hat
    danger: makeIcon('exclamation-triangle'),
    working: makeIcon('wrench')
};

module.exports = {
    blocks: {
        hint: {
            process: function (block) {
                // Available styles: info, danger, tip, working
                var style = block.args[0].trim() || 'info';

                return this.renderInline("markdown", block.body)
                  .then(function(str){
                      return '<div class="alert alert-'+CLASSES[style]+'">'
                        + ICONS[style]
                        + str
                        + '</div>';
                  });

            }
        }
    }
};