./base_virtual_type_self.nit:44,3: Error: Method or variable 'a' unknown in B.
./base_virtual_type_self.nit:45,7: Error: Method or variable 'a' unknown in B.
./base_virtual_type_self.nit:46,3: Error: Method or variable 'a' unknown in B.
./base_virtual_type_self.nit:47,7: Error: Method or variable 'a' unknown in B.