Return True if I am in the zstack.

        :param s: series
        :param c: channel
        :param t: timepoint
        :returns: :class:`bool`

def in_zstack(self, s, c, t):
        """Return True if I am in the zstack.

        :param s: series
        :param c: channel
        :param t: timepoint
        :returns: :class:`bool`
        """
        if (self.series == s
            and self.channel == c
            and self.timepoint == t):
            return True
        return False