add notes for gradient check

README.md

@@ -16,12 +16,12 @@
     print(output.shape)
 ```
 
-### Known issues:
+### Known Issues:
 
 - [ ] Gradient check w.r.t offset
 - [ ] Backward is not reentrant
 
-This is adaption of the official [Deformable-ConvNets](https://github.com/msracver/Deformable-ConvNets/tree/master/DCNv2_op).
+This is an adaption of the official [Deformable-ConvNets](https://github.com/msracver/Deformable-ConvNets/tree/master/DCNv2_op).
 I have ran the gradient check for many times with DOUBLE type. Every tensor **except offset** passes. 
 However, when I set the offset to 0.5, it passes. I'm still wondering what cause this problem. Is it because some
 non-differential points? 

test.py

@@ -136,16 +136,14 @@ def example():
     try:
         check_gradient_double()
     except TypeError:
-        print('''You can swith to double precision in dcn_v2_func.py by (un)commenting these two lines: 
-                 from _ext import dcn_v2 as _backend
-                 from _ext import dcn_v2_double as _backend''')
-        print('Your tensor may not be **double** type')
-        print('Switching to **float** type')
+        print('''****** You can swith to double precision in dcn_v2_func.py by (un)commenting these two lines: 
+                 ****** from _ext import dcn_v2 as _backend
+                 ****** from _ext import dcn_v2_double as _backend''')
+        print('****** Your tensor may not be **double** type')
+        print('****** Switching to **float** type')
 
         check_gradient()
     finally:
-        print('Note: backward is not reentrant error may not be a serious problem, '
-              'since the max error is less than 1e-7\n'
-              'Still looking for what trigger this problem')
-
-    example()
+        print('****** Note: backward is not reentrant error may not be a serious problem, '
+              '****** since the max error is less than 1e-7\n'
+              '****** Still looking for what trigger this problem')