goals1.lean:9:0: error: 1 unsolved subgoal
A : Type,
a b c : A,
Hab : eq a b,
Hbc : eq b c
⊢ eq b c
goals1.lean:9:0: error: failed to add declaration 'foo' to environment, value has metavariables
remark: set 'formatter.hide_full_terms' to false to see the complete term
  ?M_1