anchor.diff:  
                  %% Check highest header.
                  ?assertEqual({ok, BH2}, aec_chain:top_header()),
  -               %% Check heighest known block.
  +               %% Check highest known block.
                  ?assertEqual({ok, B1}, aec_chain:top_block()),
   
                  %% Check by hash.
  
positive.code: 
                 %% Check highest header.
                 ?assertEqual({ok, BH2}, aec_chain:top_header()),
                 %% Check heighest known block.
                 ?assertEqual({ok, B2}, aec_chain:top_block()),
  
                 %% Check by hash.
  
negative.code: 
               %% Check highest header.
               ?assertEqual({ok, BH2}, aec_chain:top_header()),
               %% Check highest known block - still genesis.
               ?assertEqual({ok, B0}, aec_chain:top_block()),
  
               %% Check by hash.
  