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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 downgrades(src):
 """Decorator for marking that a method is a downgrade to a version to the previous version. Parameters src : int The version this downgrades from. Returns ------- decorator : callable[(callable) -> callable] The decorator to apply. """

    def _(f):
        destination = src - 1

        @do(operator.setitem(_downgrade_methods, destination))
        @wraps(f)
        def wrapper(op, conn, version_info_table):
            conn.execute(version_info_table.delete())  # clear the version
            f(op)
            write_version_info(conn, version_info_table, destination)

        return wrapper
    return _