def __convertChannelMask(self, channelsArray):
        """convert channelsArray to bitmask format

        Args:
            channelsArray: channel array (i.e. [21, 22])

        Returns:
            bitmask format corresponding to a given channel array
        """
        maskSet = 0

        for eachChannel in channelsArray:
            mask = 1 << eachChannel
            maskSet = (maskSet | mask)

        return maskSet
convert channelsArray to bitmask format

        Args:
            channelsArray: channel array (i.e. [21, 22])

        Returns:
            bitmask format corresponding to a given channel array