// * unsigned char is used for booleans (instead of the 'bool' type).
//   In C++ bool is a keyword while in C99 bool is a macro defined
//   in stdbool.h. It is possible for the two to be inconsistent.
//   For example, neither the C99 nor the C++11 standard force a byte
//   size on the bool type, so the macro defined in stdbool.h could
//   be inconsistent with the bool keyword in C++. Thus, the use

  ///   * Must set `status` to `TF_NOT_FOUND` if one of the parents entries in
  ///     either `src` or `dst` doesn't exist or if the specified `src` path
  ///     doesn't exist.
  ///   * Must set `status` to `TF_FAILED_PRECONDITION` if either `src` or
  ///     `dst` is a directory or if either of them is invalid.
  ///   * Might use any other error value for `status` to signal other errors.
  ///