anchor.diff:      false = EmptyChannel == channel(24000),
       reveal:reveal(),
       sign_tx:sign(),
  -    
  +
       F = fun() -> sign_tx:sign(), buy_block() end,
       G = fun() -> F(), F(), F(), F(), F(), F(), F(), F() end,
       H = fun() -> G(), G(), G(), G(), G(), G(), G(), G() end,
  
positive.code:     reveal:reveal(),
      buy_block(),
      tx_pool:absorb(sign_tx(slasher_tx:slasher(1, keys:sign({sign_tx, 0, 0, 0, 0, 0, 0})), Pub, Priv)),
      Top = read(read(top)),
      CreateTx1 = to_channel_tx:create_channel(1, 10000, 1000, delegated_1, 0),
      SignedCreateTx1 = sign_tx(CreateTx1, Pub, Priv),
  
negative.code: -module(block_tree).
  -behaviour(gen_server).
  -export([start_link/0,code_change/3,handle_call/3,handle_cast/2,handle_info/2,init/1,terminate/2, long_test/0,test/0,write/1,top/0,read/1,read_int/2,read_int/1,secret/4,account/1,account/2,account/3,channel/2,channel/3,channel/1,absorb/1,is_key/1,height/1,height/0,txs/1,txs/0,power/0,power/1,block/0,block/1,buy_block/2, block_power/1,block_entropy/1,empty_block/0,total_coins/0, buy_block/0, block_number/1, block2txs/1]).
  -record(block, {acc = 0, number = 0, hash = "", txs = [], power = fractions:multiply_int(constants:initial_portion_delegated(), constants:initial_coins()), entropy = 0, total_coins = constants:initial_coins(), db_root = <<>>}).
  %power is how many coin are in channels. it is for consensus.
  block_number(B) -> B#block.number.
  