code: def _get_expiration_from_args(self):
          
          current_block = self.ident.w3.eth.blockNumber
          s = self.args.expiration
          if (s.startswith("+") and s.endswith("days")):
              rez = current_block + int(s[1:-4]) * 4 * 60 * 24
          elif (s.startswith("+") and s.endswith("blocks")):
              rez = current_block + int(s[1:-6])
          else:
              rez = int(s)
          if (rez > current_block + 1036800 and not self.args.force):
              d = (rez - current_block) // (4 * 60 * 24)
              raise Exception("You try to set expiration time too far in the future: approximately %i days. "%d +
                              "Set --force parameter if your really want to do it.")
          return rez
docs: read expiration from args.
          We allow the following types of expirations
           1. "<int>" simple integer defines absolute expiration in blocks
           2. "+<int>blocks", where <int> is integer sets expiration as: current_block + <int>
           3. "+<int>days", where <int> is integer sets expiration as: current_block + <int>*4*60*24 (we assume 15 sec/block here)
  
          If expiration > current_block + 1036800 (~6 month) we generate an exception if "--force" flag haven't been set