code: def is_valid(self) -> bool:
          '''check if VoteCast is valid'''
  
          if not (self.blocknum >= self.vote.start_block and
                  self.blocknum <= self.vote.end_block):
              return False
  
          if not self.confirmations >= 6:
              return False
  
          return Truf is_valid(self) -> bool:
          '''check if VoteCast is valid'''
  
          if not (self.blocknum >= self.vote.start_block and
                  self.blocknum <= self.vote.end_block):
              return False
  
          if not self.confirmations >= 6:
              return False
  
          return True
docs: check if VoteCast is valid