src/basis.js
function slice(source, keys){
    var result = {};

    if (!keys)
      return extend(result, source);

    for (var i = 0, key; key = keys[i++];)
      if (key in source)
        result[key] = source[key];

    return result;
  }
function slice(source, keys){
    var result = {};

    if (!keys)
      return extend(result, source);

    for (var i = 0, key; key = keys[i++];)
      if (key in source)
        result[key] = source[key];

    return result;
  }
function slice ( source , keys ) { var result = { } ; if ( ! keys ) return extend ( result , source ) ; for ( var i = 0 , key ; key = keys [ i ++ ] ; ) if ( key in source ) result [ key ] = source [ key ] ; return result ; }
Creates a slice of source object.
@param {object} source Any object can has properties.
@param {Array.<string>} keys Desired key set.
@return {object} New object with desired keys from source object.
Creates a slice of source object .