func WriterFunc(f func(ctx *Context, t *Tuple) error) Writer {
	return writerFunc(f)
}
WriterFunc creates a Writer from a function.
package core
type Writer interface {
	Write(ctx *Context, t *Tuple) error
}
type WriteCloser interface {
	Writer
	Close(ctx *Context) error
}
type writerFunc func(ctx *Context, t *Tuple) error