callGraph' f@(Global id dataenv) (TEGlobLet _ id' _ body)
  | id == id' = callGraph' f body
  | otherwise =
     throwError $ CallGraphError "Attempt to generate call graph for mismatching control point and definition."
callGraph' f@(Global id dataenv) (TEGlobLet _ id' _ body)
  | id == id' = callGraph' f body
  | otherwise =
     throwError $ CallGraphError "Attempt to generate call graph for mismatching control point and definition."
callGraph' f@(Global id dataenv) (TEGlobLet _ id' _ body)
  | id == id' = callGraph' f body
  | otherwise =
     throwError $ CallGraphError "Attempt to generate call graph for mismatching control point and definition."