AMR/node_modules/csso/lib/compressor/clean/index.js

var walk = require('../../utils/walk.js').all;
var handlers = {
    Space: require('./Space.js'),
    Atrule: require('./Atrule.js'),
    Ruleset: require('./Ruleset.js'),
    Declaration: require('./Declaration.js'),
    Identifier: require('./Identifier.js'),
    Comment: require('./Comment.js')
};

module.exports = function(ast, usageData) {
    walk(ast, function(node, item, list) {
        if (handlers.hasOwnProperty(node.type)) {
            handlers[node.type].call(this, node, item, list, usageData);
        }
    });
};