Whether a channel is a member of a group's member list. The canonical membership test: two channel refs match when their channelKeys are equal (structural, not reference, equality).
a group's member channel refs
the channel to test for membership
true if id is in members
true
id
members
Whether a channel is a member of a group's member list. The canonical membership test: two channel refs match when their channelKeys are equal (structural, not reference, equality).