anchor.diff:              %%    but unstable: we're probably going to flap back & forth?!
   
               ?D({{{{{yoyoyo_A40c}}}}}),
  -            react_to_env_C300(P_newprop, S);
  +            react_to_env_C300(P_newprop, P_latest, S);
   
           true ->
               {{no_change, P_latest#projection.epoch_number}, S}
  
positive.code: 
          %% A40a (see flowchart)
          Rank_newprop > Rank_latest ->
              react_to_env_C300(P_newprop, S);
  
          %% A40b (see flowchart)
          P_latest#projection.author_server == MyFLU
  
negative.code: 
              %% The author of P_latest is too slow or crashed.
              %% Let's try to write P_newprop and see what happens!
              react_to_env_C300(P_newprop, P_latest, S);
  
          Rank_latest >= Rank_newprop
          andalso
  