  A tool package for computing genus 0 Belyi functions is presented, including
simplification routines, computation of moduli fields, decompositions, dessins
d'enfant. The main algorithm for computing the Belyi functions themselves is
based on implied transformations of the hypergeometric differential equation to
Fuchsian equations, preferably with few singular points. This gives interesting
differential relations between polynomial components of a Belyi function.
