code: def lnlike(x, star):
      
      ll = lnprior(x)
      if np.isinf(ll):
          return ll, (np.nan, np.nan)
      per, t0, b = x
      model = TransitModel('b', per=per, t0=t0, b=b, rhos=10.)(star.time)
      like, d, vard = star.lnlike(model, full_output=True)
      ll += like
      return ll, (d,)
docs: Return the log likelihood given parameter vector `x`.