def is_stream_binary_plist(stream):
    """
    Module function to check, if the stream is a binary plist.
    
    @param stream plist stream (file object)
    @return flag indicating a binary plist (boolean)
    """
    stream.seek(0)
    header = stream.read(7)
    if header == b'bplist0':
        return True
    else:
        return False
