code: def exists(self, primary_key):
          
          '''
              a method to determine if record exists
              
          :param primary_key: string with primary key of record 
          :return: boolean to indicate existence of record
          '''
          
          select_statement = self.table.select(self.table).where(self.table.c.id==primary_key)
          record_object = self.session.execute(select_statement).first()
          if record_object:
              return True
          return Falsf exists(self, primary_key):
          
          '''
              a method to determine if record exists
              
          :param primary_key: string with primary key of record 
          :return: boolean to indicate existence of record
          '''
          
          select_statement = self.table.select(self.table).where(self.table.c.id==primary_key)
          record_object = self.session.execute(select_statement).first()
          if record_object:
              return True
          return False
docs: a method to determine if record exists
              
          :param primary_key: string with primary key of record 
          :return: boolean to indicate existence of record