code: function( wcs, options, callback ) {
  	if ( typeof options === 'function' ) {
  		callback = options;
  		options = null;
  	}
  	if ( !Array.isArray( wcs ) ) {
  		wcs = [wcs];
  	}
  	options = options || {};
  	addExtraOptions( [ 'force', 'quiet', 'revision', 'depth', 'ignoreExternals' ], options );
  	executeSvn( [ 'update' ].concat( wcs ), options, callback );
  }
docs: Updates an svn working copy
  @function update
  @memberof commands
  @param {Array|string} wcs - Working copy targets
  @param {object} [options] - Options object
  @param {function} [callback] - Complete callback
  @alias up