Net::HTTPHeader#connection_keep_alive?

# File tmp/rubies/ruby-3.0.5/lib/net/http/header.rb, line 509
def connection_keep_alive?
  token = /(?:\A|,)\s*keep-alive\s*(?:\z|,)/i
  @header['connection']&.grep(token) {return true}
  @header['proxy-connection']&.grep(token) {return true}
  false
end