class RuboCop::Cop::Security::Open

def safe?(node)
  if node.str_type?
    !node.str_content.empty? && !node.str_content.start_with?('|')
  elsif node.dstr_type?
    safe?(node.child_nodes.first)
  elsif node.send_type? && node.method_name == :+
    safe?(node.child_nodes.first)
  else
    false
  end
end