def getFeatureID(self, location):
    """
    Returns the feature index associated with the provided location.

    In the case of a sphere, it is always the same if the location is valid.
    """
    truthyFeature = self.contains(location)
    if not truthyFeature:
      return self.EMPTY_FEATURE
    elif truthyFeature=='face':
      return self.FLAT
    elif truthyFeature=='vertex':
      return self.POINTY
    elif truthyFeature=="edge":
      return self.EDGE
    elif truthyFeature=="surface":
      return self.SURFACE
    else:
      return self.EMPTY_FEATURE