(writer, segments)
return []
This policy DELETES all existing segments and only writes the new
    segment.
This policy DELETES all existing segments and only writes the new
    segment.
This policy DELETES all existing segments and only writes the new segment .
def CLEAR(writer, segments):
    """This policy DELETES all existing segments and only writes the new
    segment.
    """

    return []
def CLEAR ( writer , segments ) : return [ ]