Fix next unique (#3071)
Fix next unique (#3071)

* fix next_unique

Signed-off-by: daquexian <f5f37435e17c9e411096cd88a2a730c74bd07a78@gmail.com>

* fix

Signed-off-by: daquexian <f5f37435e17c9e411096cd88a2a730c74bd07a78@gmail.com>

* check subgraph, refine the code style

Signed-off-by: daquexian <f5f37435e17c9e411096cd88a2a730c74bd07a78@gmail.com>

* address comments

Signed-off-by: daquexian <f5f37435e17c9e411096cd88a2a730c74bd07a78@gmail.com>

* fix the return value of 'isNameUnique'

Signed-off-by: daquexian <f5f37435e17c9e411096cd88a2a730c74bd07a78@gmail.com>

Co-authored-by: sandman7 <dc0cdf96053b94d2abbdb00c3cc63fba1f2e0856@gmail.com>
Co-authored-by: Ashwini Khade <c033833d70de1f14d546d5b23d66cc02095a83ed@microsoft.com>
onnx/onnx,onnx/onnx,onnx/onnx,onnx/onnx