text: from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy import Column, Integer, String, ForeignKey
  from sqlalchemy.types import DateTime
  
  Base = declarative_base()
  
  class Building(Base):
      __tablename__ = "buildings"
  
      id = Column(Integer, primary_key=True)
      name = Column(String)
  
  class MachineType(Base):
      __tablename__ = "machinetypes"
  
      id = Column(Integer, primary_key=True)
      name = Column(String)
  
  class Machine(Base):
      __tablename__ = "machines"
  
      id = Column(Integer, primary_key=True)
      tufts_id = Column(Integer)
      room = Column(Integer, ForeignKey("buildings.id"))
      type = Column(Integer, ForeignKey("machinetypes.id"))
  
  
  class UsageRecord(Base):
      __tablename__ = "usagerecords"
  
      id = Column(Integer, primary_key=True)
      machine = Column(Integer, ForeignKey("machines.id"))
      available = Column(Integer)
      time_remaining = Column(Integer)
      timestamp = Column(DateTime)