emptyTypeAscription.lean:3:19-3:24: error: invalid dotted identifier notation, expected type is not of the form (... → C ...) where C is a constant
  ?m
emptyTypeAscription.lean:4:29-4:34: error: invalid dotted identifier notation, expected type is not of the form (... → C ...) where C is a constant
  ?m
emptyTypeAscription.lean:9:63-9:70: error: invalid `▸` notation, expected result type of cast is 
  w = add x y
however, the equality 
  h₁
of type 
  z = x + y
does not contain the expected result type on either the left or the right hand side
emptyTypeAscription.lean:10:55-10:62: error: invalid `▸` notation, expected result type of cast is 
  w = add x y
however, the equality 
  h₁
of type 
  z = x + y
does not contain the expected result type on either the left or the right hand side