class Acme::Client

def new_certificate(csr)
  payload = {
    resource: 'new-cert',
    csr: Base64.urlsafe_encode64(csr.to_der)
  }
  response = connection.post(@operation_endpoints.fetch('new-cert'), payload)
  ::Acme::Client::Certificate.new(OpenSSL::X509::Certificate.new(response.body), response.headers['location'], fetch_chain(response), csr)
end