code: function mixinConstructor(source)
  {
    var keys = Object.keys(source)
      , i    = keys.length
      ;
  
    while (i-- > 0) {
      this[keys[i]] = source[keys[i]];
    }
  }
docs: Populates instance with provided properties (shallow copy)
  
  @private
  @param   {object} source - source object to copy properties from
  @returns {void}