1 base_isa_nil.nit:33,2--13: Warning: Expression is already a Object.
2 base_isa_nil.nit:36,2--22: Warning: Expression is already a nullable Object since it is a Object.
3 base_isa_nil.nit:40,2--13: Warning: Prefer '!= null'.
4 base_isa_nil.nit:43,2--22: Warning: Expression is already a nullable Object.