decoderMember = decoder => ({
  memberId: decoder.readString(),
  clientId: decoder.readString(),
  clientHost: decoder.readString(),
  memberMetadata: decoder.readBytes(),
  memberAssignment: decoder.readBytes(),
})
DescribeGroups Response (Version: 0) => [groups]
  groups => error_code group_id state protocol_type protocol [members]
    error_code => INT16
    group_id => STRING
    state => STRING
    protocol_type => STRING
    protocol => STRING
    members => member_id client_id client_host member_metadata member_assignment
      member_id => STRING
      client_id => STRING
      client_host => STRING
      member_metadata => BYTES
      member_assignment => BYTES