In `The Wizard of Oz`, while Dorothy is still in Kansas before the tornado, the mean old lady Mrs. Gulch, from a couple farms over who rode the bicycle and kept threatening Toto had sort of a menacing little tune/melody that plays while she is riding along. 

Is that tune an original composition for her, for the movie, or is it based on some prior piece of work and was re-used/adapted for use in Oz?