Singhvi: it is completely artifical distinction dichotomy made between withholding and returning- withholding must lead to return. There aren't separate options.

Proviso is directly linked to the second option-withholding is the first step and returning is the second step. Last line-shall not withhold assent is the same as the body

CJI: first option is to give assent, third is to send to President

Singhvi: that's why the proviso meant for the second option. Saying he can withhold simplicter, it will make a mockery of whole proviso