What is the test for determining whether there is any substantial evidence to support an allegation of sexual assault?

" '[O]ur power begins and ends with a determination as to whether there is any substantial evidence to support [the findings]; ... we have no power to judge of the effect or value of the evidence, to weigh the evidence, to consider the credibility of the witnesses, or to resolve conflicts in the evidence or in the reasonable inferences that may be drawn therefrom.' [Citations.]" (Leff v. Gunter (1983) 33 Cal.3d 508, 518, 189 Cal.Rptr. 377, 658 P.2d 740.)