class RuboCop::Cop::Style::MultilineIfModifier

def on_if(node)
  return if part_of_ignored_node?(node)
  return unless node.modifier_form? && node.body.multiline?
  add_offense(node, message: format(MSG, keyword: node.keyword)) do |corrector|
    corrector.replace(node, to_normal_if(node))
  end
  ignore_node(node)
end