class RuboCop::Cop::Style::ParallelAssignment

`self.a, self.b = b, a`.
This makes the sorting algorithm work for expressions such as
Converts (send nil :something) nodes to (send (:self) :something).

def add_self_to_getters(right_elements)
  right_elements.map do |e|
    implicit_self_getter?(e) { |var| s(:send, s(:self), var) } || e
  end
end