class RuboCop::Cop::Style::TrivialAccessors

def looks_like_trivial_writer?(args, body)
  args.children.size == 1 &&
    ![:restarg, :blockarg].include?(args.children[0].type) &&
    body && body.type == :ivasgn &&
    body.children[1] && body.children[1].type == :lvar
end