old_contents: from sqlalchemy import Column, Integer
  from sqlalchemy.orm import relationship
  
  from scoring_engine.models.base import Base
  
  
  class Round(Base):
      __tablename__ = "rounds"
      id = Column(Integer, primary_key=True)
      number = Column(Integer, nullable=False)
      checks = relationship("Check", back_populates="round")
  
      @staticmethod
      def get_last_round_num():
          round_obj = Round.query.order_by(Round.number.desc()).first()
          if round_obj is None:
              return 0
          else:
              return round_obj.number
  
new_contents: import datetime
  from sqlalchemy import Column, DateTime, Integer
  from sqlalchemy.orm import relationship
  
  from scoring_engine.models.base import Base
  
  
  class Round(Base):
      __tablename__ = "rounds"
      id = Column(Integer, primary_key=True)
      number = Column(Integer, nullable=False)
      checks = relationship("Check", back_populates="round")
      round_start = Column(DateTime, default=datetime.datetime.utcnow)
      round_end = Column(DateTime)
  
      @staticmethod
      def get_last_round_num():
          round_obj = Round.query.order_by(Round.number.desc()).first()
          if round_obj is None:
              return 0
          else:
              return round_obj.number
  
subject: Add start and end times for rounds