instance_cache1.lean:3:2: error: failed to synthesize type class instance for A : Type ?, a : A, this : has_add A ⊢ has_add A instance_cache1.lean:1:11: warning: declaration 'f1' uses sorry instance_cache1.lean:6:7: error: failed to synthesize type class instance for A : Type ?, a : A, s : has_add A ⊢ has_add A instance_cache1.lean:5:11: warning: declaration 'f2' uses sorry instance_cache1.lean:9:19: error: failed to synthesize type class instance for A : Type ?, a : A, s : has_add A ⊢ has_add A instance_cache1.lean:8:11: warning: declaration 'f3' uses sorry