code: def propose_unif(self):
          
  
          while True:
              # Sample a point from the ellipsoid.
              u = self.ell.sample(rstate=self.rstate)
  
              # Check if `u` is within the unit cube.
              if unitcheck(u, self.nonperiodic):
                  break  # if it is, we're done!
  
          return u, self.ell.axes
docs: Propose a new live point by sampling *uniformly*
          within the ellipsoid.