But that information disappears when you assign to an interface variable/container that is nillable. It requires an assertion to recover the info about the valu

But that information disappears when you assign to an interface variable/container that is nillable. It requires an assertion to recover the info about the value inside the interface being not nil. basically `if v.(nil){...} creates two branches. In one we know v is not nil (outside the if block) and it can therefore be assigned to non nillable variables so to speak...