code: function streamFactory( options ) {
  	var opts;
  	if ( arguments.length ) {
  		opts = copy( options );
  	} else {
  		opts = {};
  	}
  	/**
  	* FUNCTION: createStream( fcn )
  	*	Creates a stream.
  	*
  	* @param {Function} fcn - map function
  	* @returns {Stream} Transform stream
  	*/
  	return function createStream( fcn ) {
  		if ( !arguments.length ) {
  			throw new Error( 'insufficient input arguments. Must provide a map function.' );
  		}
  		return new Stream( opts, fcn );
  	};
  }
docs: FACTORY // 
  FUNCTION: streamFactory( [options] )
  Creates a reusable stream factory.
  
  @param {Object} [options] - stream options
  @param {Number} [options.highWaterMark=16] - specifies the Buffer level for when `write()` starts returning `false`
  @param {Boolean} [options.allowHalfOpen=false] - specifies whether a stream should remain open even if one side ends
  @returns {Function} stream factory