class RuboCop::Cop::Lint::UselessAssignment

def operator_assignment_message(scope, assignment)
  return_value_node = return_value_node_of_scope(scope)
  return unless assignment.meta_assignment_node
                          .equal?(return_value_node)
  " Use `#{assignment.operator.sub(/=$/, '')}` " \
  "instead of `#{assignment.operator}`."
end