add sign & Sequential __iter__

python/jittor/nn.py

@@ -142,6 +142,9 @@ def get_init_var_rand(shape, dtype):
 def relu(x): return jt.maximum(x, 0)
 def leaky_relu(x, scale=0.01): return jt.ternary(x>0, x, x*scale)
 def relu6(x): return jt.minimum(jt.maximum(x, 0), 6)
+def sign(x): 
+    x = jt.ternary(x>0, jt.ones(x.shape), x)
+    return jt.ternary(x<0, -1*jt.ones(x.shape), x)
 
 def gelu(x):
     _sqrt2 = 1.4142135623730951
@@ -1170,6 +1173,9 @@ class Sequential(Module):
                     self.append(m)
             else:
                 self.append(mod)
+    def __iter__(self):
+        for v in self.layers.values():
+            yield v
     def __getitem__(self, idx):
         return self.layers[idx]
     def __iter__(self):