impure_method_impl.m:026: In type class method implementation:
impure_method_impl.m:026:   purity error: predicate is semipure.
impure_method_impl.m:026:   It must be declared `semipure' or promised pure.
impure_method_impl.m:026: In call to semipure predicate
impure_method_impl.m:026:   `impure_method_impl.foo_m1'/2:
impure_method_impl.m:026:   purity error: call must be preceded by `semipure'
impure_method_impl.m:026:   indicator.
impure_method_impl.m:027: In type class method implementation:
impure_method_impl.m:027:   purity error: predicate is impure.
impure_method_impl.m:027:   It must be declared `impure' or promised semipure.
impure_method_impl.m:027: In call to impure predicate
impure_method_impl.m:027:   `impure_method_impl.foo_m2'/2:
impure_method_impl.m:027:   purity error: call must be preceded by `impure'
impure_method_impl.m:027:   indicator.