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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 Svn(url, fname, to=None):
 """ Checkout the SVN repo. Args: url (str):
 The SVN SOURCE repo. fname (str):
 The name of the repo on disk. to (str):
 The name of the TARGET folder on disk. Defaults to ``CFG["tmpdir"]`` """

    if to is None:
        to = str(CFG["tmp_dir"])

    src_dir = local.path(to) / fname
    if not source_required(src_dir):
        Copy(src_dir, ".")
        return

    from benchbuild.utils.cmd import svn
    svn("co", url, src_dir)
    update_hash(src_dir)
    Copy(src_dir, ".")