code: def zero(self):
          
          return self.element(np.zeros(self.shape, dtype=self.dtype,
                                       order=self.default_order))
docs: Return a tensor of all zeros.
  
          Examples
          --------
          >>> space = odl.rn(3)
          >>> x = space.zero()
          >>> x
          rn(3).element([ 0.,  0.,  0.])