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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 copytree(src, dst):
 """Replaces shutil.copytree to avoid problems on certain file systems. shutil.copytree() and shutil.copystat() invoke os.setxattr(), which seems to fail when called for directories on at least one NFS file system. The current routine is a simple replacement, which should be good enough for Ford. """

    def touch(path):
        now = time.time()
        try:
            # assume it's there
            os.utime(path, (now, now))
        except os.error:
            # if it isn't, try creating the directory,
            # a file with that name
            os.makedirs(os.path.dirname(path))
            open(path, "w").close()
            os.utime(path, (now, now))

    for root, dirs, files in os.walk(src):
        relsrcdir = os.path.relpath(root, src)
        dstdir = os.path.join(dst, relsrcdir)
        if not os.path.exists(dstdir):
            try:
                os.makedirs(dstdir)
            except OSError as ex:
                if ex.errno != errno.EEXIST:
                    raise
        for ff in files:
            shutil.copy(os.path.join(root, ff), os.path.join(dstdir, ff))
            touch(os.path.join(dstdir, ff))