My McCartney Moment

The story goes that Paul McCartney fell out of bed one morning with the whole melody of "Yesterday" in his head. He was sure he had heard it somewhere and kept asking people if they knew the tune, but no-one did. Of course, the story might have been embroidered a bit: maybe he only had a piece of it and the rest came to him over a few days.

I'm writing a guitar piece right now, improvising and sketching in pencil every morning and one day I just had this little fragment of a melody pop into my head. It seems obviously Latin-American and I seemed to recall it from somewhere. But I looked around in some obvious places: Venezuelan waltzes, an anthology of Latin-American folk tunes, Barrios, but I didn't see it anywhere. So I put it to the readership: do you know this tune?