function TransformStream( options ) { // eslint-disable-line stdlib/no-redeclare
	var opts;
	var err;
	if ( !( this instanceof TransformStream ) ) {
		if ( arguments.length ) {
			return new TransformStream( options );
		}
		return new TransformStream();
	}
	opts = assign( {}, DEFAULTS );
	if ( arguments.length ) {
		err = validate( opts, options );
		if ( err ) {
			throw err;
		}
	}
	debug( 'Creating a transform stream configured with the following options: %s.', JSON.stringify( opts ) );
	Transform.call( this, opts );
	this._destroyed = false;
	if ( opts.transform ) {
		this._transform = opts.transform;
	} else {
		this._transform = _transform;
	}
	if ( opts.flush ) {
		this._flush = opts.flush;
	}
	return this;
}
Transform stream constructor.

@constructor
@param {Options} [options] - stream options
@param {Function} [options.transform] - callback to invoke upon receiving a new chunk
@param {Function} [options.flush] - callback to invoke after receiving all chunks and prior to the stream closing
@param {boolean} [options.objectMode=false] - specifies whether 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.decodeStrings=true] - specifies whether to decode `strings` into `Buffer` objects when writing
@throws {TypeError} must provide valid options
@returns {TransformStream} transform stream

@example
var stdout = require( '@stdlib/streams/node/stdout' );

function transform( chunk, enc, clbk ) {
    clbk( null, chunk.toString()+'\n' );
}

var opts = {
    'transform': transform
};
var stream = new TransformStream( opts );

stream.pipe( stdout );

stream.write( '1' );
stream.write( '2' );
stream.write( '3' );

stream.end();

// prints: '1\n2\n3\n'