code: function extend(t, s) {
      for (var k in s.prototype) {
          t.prototype[k] = s.prototype[k];
      }
      return t;
  }
docs: /*
  @function extend(t, s) Extends the target class @c t with all the prototypes
  of class @c s.
  @param {Object} t target object
  @param {Object} s source object