Net::HTTPSession#keep_alive?

# File tmp/rubies/ruby-3.4.1/lib/net/http.rb, line 2496
def keep_alive?(req, res)
  return false if req.connection_close?
  if @curr_http_version <= '1.0'
    res.connection_keep_alive?
  else   # HTTP/1.1 or later
    not res.connection_close?
  end
end