code: function inherit(child, base, properties) {
      var baseP = base.prototype,
          childP;
  
      childP = child.prototype = Object.create(baseP);
      childP.constructor = child;
      childP._super = baseP;
  
      if (properties) {
          assign(childP, properties);
      }
  }
docs: simple class inheritance
  @param {Function} child
  @param {Function} base
  @param {Object} [properties]