code: def validate(self):
          ''' Perform integrity checks on the modes in this document.
  
          Returns:
              None
  
          '''
          for r in self.roots:
              refs = r.references()
              check_integrity(refsf validate(self):
          ''' Perform integrity checks on the modes in this document.
  
          Returns:
              None
  
          '''
          for r in self.roots:
              refs = r.references()
              check_integrity(refs)
docs: Perform integrity checks on the modes in this document.
  
          Returns:
              None