code: def refactor_use_function(self, offset):
          
          try:
              refactor = UseFunction(self.project, self.resource, offset)
          except RefactoringError as e:
              raise Fault(
                  'Refactoring error: {}'.format(e),
                  code=400
              )
          return self._get_changes(refactor)
docs: Use the function at point wherever possible.