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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def setns(fd, nstype):
 """ Reassociate thread with a namespace :param fd int: The file descriptor referreing to one of the namespace entries in a :directory::`/proc/<pid>/ns/` directory. :param nstype int: The type of namespace the calling thread should be reasscoiated with. """

    res = lib.setns(fd, nstype)
    if res != 0:
        _check_error(ffi.errno)