class RuboCop::Cop::Sorbet::SelectByIsA

def on_send(node)
  block_node = node.block_node
  return unless block_node
  return unless type_narrowing_select?(block_node)
  add_offense(block_node) do |corrector|
    receiver = node.receiver
    type_class = block_node.body.children[2]
    navigation = node.csend_type? ? "&." : "."
    replacement = "#{receiver.source}#{navigation}grep(#{type_class.source})"
    corrector.replace(block_node, replacement)
  end
end