fix python2

python/fluid.py

@@ -147,7 +147,7 @@ class FluidProblem :
             raise NameError("Pressure or Velocity (but not both) should be specified at open boundaries")
         if velocity is not None :
             n_value = self._dim+self._n_fluids-1    # u, v, w, a
-            cb_or_value = [*velocity,concentration] if self._n_fluids == 2 else velocity
+            cb_or_value = velocity+[concentration] if self._n_fluids == 2 else velocity
             bnd_type = "velocity"
         else :
             n_value = self._n_fluids                # p, a