use std::fmt::{self, Display, Formatter};

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[non_exhaustive]
pub enum AuthAccessType {
    Read,
    Write,
}

    }
}
impl AuthAccessType {
    pub fn as_str(&self) -> &'static str {
        match *self {
            AuthAccessType::Read => "read",
            AuthAccessType::Write => "write",
        }
    }
}
impl AsRef<str> for AuthAccessType {
    fn as_ref(&self) -> &str {
        self.as_str()

impl Display for AuthAccessType {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        f.write_str(self.as_ref())
    }
}

    x_auth_access_type: Option<AuthAccessType>,

    let req = request_token_request(client_credentials.as_ref());

    let req = request_token_request(client_credentials.as_ref(), x_auth_access_type);

fn request_token_request(client_credentials: Credentials<&str>) -> http::Request<()> {

fn request_token_request(
    client_credentials: Credentials<&str>,
    x_auth_access_type: Option<AuthAccessType>,
) -> http::Request<()> {

    #[derive(oauth::Request)]
    struct RequestToken {
        x_auth_access_type: Option<AuthAccessType>,
    }

        .post(URI, &());

        .post(URI, &RequestToken { x_auth_access_type });