human
Complete this python program:
def downgrades(src):
assistant
#Here is the Python program you requested.

    """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(op.setitem(_downgrade_methods, destination))
        @wraps(f)
        def wrapper(op, conn, version_info_table):
            conn.execute(version_info_table.delete())
            f(op)
            write_version_info(conn, version_info_table, destination)
        return wrapper
    return _