sS googleOAuthRedirectURL(S redirect_uri, S client_id, S scope) {
  ret "https://accounts.google.com/o/oauth2/v2/auth"
    + hquery(+scope,
      access_type := "offline",
      //approval_prompt := "force",
      prompt := "consent",
      include_granted_scopes := true,
      response_type := "code",
      state := 1234,
      +redirect_uri,
      +client_id);
}