Before starting to code, it is necessary to solve the problem of interface.

With the majority of the functions all is good, but the `link` and `rename` have two `dirfd` parameters (even with different names). So I suggest two more alternatives.

One is the filename and dirfd are combined in a tuple. Instead of a tuple, you can specify only the name.

  link ((srcpath, srcdirfd), (dstpath, dstdirfd), *, followlinks=True)

The other -- `dirfd`s are combined in a tuple. You can specify a number, then `dirfd` is the same for both filenames.

  link (srcpath, dstpath, *, followlinks=True, dirfd=(srcdirfd, dstdirfd))

Which of these options (or the original, with different keywords) is preferable?