@NotNull
  @Override
  public final PsiElementVisitor buildVisitor(@NotNull ProblemsHolder holder,
                                              final boolean isOnTheFly,
                                              @NotNull final LocalInspectionToolSession session) {
    final PyUnresolvedReferencesVisitor visitor = createVisitor(holder, session);
    // buildVisitor() will be called on injected files in the same session - don't overwrite if we already have one
    final PyUnresolvedReferencesVisitor existingVisitor = session.getUserData(KEY);
    if (existingVisitor == null) {
      session.putUserData(KEY, visitor);
    }
    return visitor;
  }
@NotNull
  @Override
  public final PsiElementVisitor buildVisitor(@NotNull ProblemsHolder holder,
                                              final boolean isOnTheFly,
                                              @NotNull final LocalInspectionToolSession session)