code: def get_fast_scanner(self):
          r
          from numpy_sugar.linalg import ddot, economic_qs, sum2diag
  
          y = self.eta / self.tau
  
          if self._QS is None:
              K = eye(y.shape[0]) / self.tau
          else:
              Q0 = self._QS[0][0]
              S0 = self._QS[1]
              K = dot(ddot(Q0, self.v0 * S0), Q0.T)
              K = sum2diag(K, 1 / self.tau)
  
          return FastScanner(y, self._X, economic_qs(K), self.v1)
docs: r"""Return :class:`glimix_core.lmm.FastScanner` for the current
          delta.