function streamFactory( options ) {
	var opts;
	if ( arguments.length ) {
		if ( !isObject( options ) ) {
			throw new TypeError( format( 'invalid argument. Options argument must be an object. Value: `%s`.', options ) );
		}
		opts = assign( {}, options );
	} else {
		opts = {};
	}
	return joinStream;

	/**
	* Creates a transform stream for joining streamed data.
	*
	* @private
	* @throws {TypeError} must provide valid options
	* @returns {JoinStream} join stream
	*/
	function joinStream() {
		return new Stream( opts );
	}
}
Creates a reusable join stream factory.

@param {Options} [options] - stream options
@param {string} [options.sep='\n'] - separator used to join streamed data
@param {boolean} [options.objectMode=false] - specifies whether a stream should operate in object mode
@param {(string|null)} [options.encoding=null] - specifies how `Buffer` objects should be decoded to `strings`
@param {NonNegativeNumber} [options.highWaterMark] - specifies the `Buffer` level for when `write()` starts returning `false`
@param {boolean} [options.allowHalfOpen=false] - specifies whether the stream should remain open even if one side ends
@param {boolean} [options.readableObjectMode=false] - specifies whether the readable side should be in object mode
@throws {TypeError} options argument must be an object
@returns {Function} join stream factory

@example
var opts = {
    'sep': '\t',
    'objectMode': true,
    'encoding': 'utf8',
    'highWaterMark': 64
};

var factory = streamFactory( opts );

// Create 10 identically configured streams...
var streams = [];
var i;
for ( i = 0; i < 10; i++ ) {
    streams.push( factory() );
}