use std::convert::TryFrom; /// A scheme for use in a [`Url`][crate::Url].#[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone)]#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]#[allow(missing_docs)]pub enum Scheme {    File,    Git,    Ssh,    Http,    Https,    Ext(String),} impl<'a> TryFrom<&'a str> for Scheme {    type Error = &'a str;     fn try_from(value: &'a str) -> Result<Self, Self::Error> {        Ok(match value {            "ssh" => Scheme::Ssh,            "file" => Scheme::File,            "git" => Scheme::Git,            "http" => Scheme::Http,            "https" => Scheme::Https,            "rad" => Scheme::Ext("rad".into()),            unknown => return Err(unknown),        })    }} impl Scheme {    /// Return ourselves parseable name.    pub fn as_str(&self) -> &str {        use Scheme::*;        match self {            File => "file",            Git => "git",            Ssh => "ssh",            Http => "http",            Https => "https",            Ext(name) => name.as_str(),        }    }} impl std::fmt::Display for Scheme {    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {        f.write_str(self.as_str())    }}