anchor.diff:  
   -type(decision_hint() :: my_proposal_won | had_no_proposal).
   
  --type(group_id() :: non_neg_integer()).
  -
   -type(group_node() :: {GroupId::group_id(),
                          Version::non_neg_integer(),
                          Members::list(comm:mypid())}).
  
positive.code: 
  -include("scalaris.hrl").
  
  -type(paxos_id() :: {group_id(), pos_integer()}).
  
  -type(proposal() :: {group_node_join, Pid::comm:mypid(), Acceptor::comm:mypid(),
  
negative.code:                   | {group_node_remove, Pid::comm:mypid()}
                    | {group_split, Proposer::comm:mypid(), SplitKey::?RT:key(),
                       LeftGroup::list(comm:mypid()), RightGroup::list(comm:mypid())}
                    | {read, Key::?RT:key(), Value::any(), Version::pos_integer(),
                       Client::comm:mypid(), Proposer::comm:mypid()}
                    | {write, Key::?RT:key(), Value::any(), Version::pos_integer(),
                       Client::comm:mypid(), Proposer::comm:mypid()}).
  
  -type(mode_type() :: joining | joined).
  
  