AugAssigned value depend on r-value type dependencies.

        It is valid for subscript, `a[i] += foo()` means `a` type depend on
        `foo` return type and previous a types too.

def visit_AugAssign(self, node):
        """
        AugAssigned value depend on r-value type dependencies.

        It is valid for subscript, `a[i] += foo()` means `a` type depend on
        `foo` return type and previous a types too.
        """
        args = (self.naming[get_variable(node.target).id],
                self.visit(node.value))
        merge_dep = list({frozenset.union(*x)
                          for x in itertools.product(*args)})
        self.naming[get_variable(node.target).id] = merge_dep