def __str__(self):
    x = ''
    first = True
    for i in self._list:
        if first:
            x += str(i)
            first = False
        else:
            x += (', ' + str(i))
    return ('(timestamp=%s, [%s]' % (self.timestamp, x))
def __str__(self):
    x = 
    first = True
    for i in self._list:
        if first:
            x += str(i)
            first = False
        else:
            x += (', ' + str(i))
    return ('(timestamp=%s, [%s]' % (self.timestamp, x))