public static @Nullable String getFlatMapOperationName(PsiType inType, PsiType outType) {
    if (!(inType instanceof PsiPrimitiveType)) {
      if (PsiTypes.intType().equals(outType)) {
        return "flatMapToInt";
      }
      else if (PsiTypes.longType().equals(outType)) {
        return "flatMapToLong";
      }
      else if (PsiTypes.doubleType().equals(outType)) {
        return "flatMapToDouble";
      }
    } else if (!inType.equals(outType)) return null;
    return "flatMap";
  }
public static @Nullable String getFlatMapOperationName(PsiType inType, PsiType outType)