text: import hashlib
  import json
  import http.server
  import socketserver
  import time
  from datetime import datetime
  import concurrent.futures
  import requests
  import random
  
  def _gen_block(arg):
    source_host, data, prev_hash = arg
  
    now = time.time()
    tik = datetime.fromtimestamp(now)
    timestamp = tik.timestamp()
   
    while True:
      nonce = random.randint(0, 10000000000)
      block = { \
        'timestamp':timestamp, \
        'source_host':source_host, \
        'data':data, \
        'prev_hash': prev_hash,  \
        'nonce':nonce,
      }
      next_hash = hashlib.sha256(bytes(json.dumps(block),'utf8')).hexdigest()
  
      size = 2
      if next_hash[:size] == '0'*size:
        break
    open('cache/{next_hash}', 'w').write( json.dumps(block, indent=2, ensure_ascii=False) ) 
    print('block:{0}'.format(block))
    print('next_hash:{0}'.format(next_hash))
    return block, next_hash
  
  start_block, next_hash = _gen_block(('http://localhost:8080', 'GMOインターネットグループ スピリットベンチャー宣言 2017.06.06 改定', hashlib.sha256(bytes('0', 'utf8')).hexdigest()))
  for line in open('sv/sv.txt'):
    line = line.strip()
    block, next_hash = _gen_block(('http://localhost:8080', line, next_hash) )
  