code: def getbugfields(self, force_refresh=False):
          
          if force_refresh or not self._cache.bugfields:
              log.debug("Refreshing bugfields")
              self._cache.bugfields = self._getbugfields()
              self._cache.bugfields.sort()
              log.debug("bugfields = %s", self._cache.bugfields)
  
          return self._cache.bugfields
docs: Calls getBugFields, which returns a list of fields in each bug
          for this bugzilla instance. This can be used to set the list of attrs
          on the Bug object.