/// Origin of the argument's value
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
#[non_exhaustive]
pub enum ValueSource {
/// Value came [`Arg::default_value`][crate::Arg::default_value]
DefaultValue,
/// Value came [`Arg::env`][crate::Arg::env]
EnvVariable,
/// Value was passed in on the command-line
CommandLine,
}