isFlatExp (App _ a b) = isName a && isName b
  where isName (Var{}) = True
        isName _ = False
isFlatExp (App _ a b) = isName a && isName b
  where isName (Var{}) = True
        isName _ = False
isFlatExp (App _ a b) = isName a && isName b
  where isName (Var{}) = True
        isName _ = False