/// An unvalidated parse result of parsing input like `remote.origin.url` or `core.bare`.#[derive(Debug, PartialEq, Ord, PartialOrd, Eq, Hash, Clone, Copy)]pub struct Key<'a> {    /// The name of the section, like `core` in `core.bare`.    pub section_name: &'a str,    /// The name of the sub-section, like `origin` in `remote.origin.url`.    pub subsection_name: Option<&'a str>,    /// The name of the section key, like `url` in `remote.origin.url`.    pub value_name: &'a str,} /// Parse `input` like `core.bare` or `remote.origin.url` as a `Key` to make its fields available,/// or `None` if there were not at least 2 tokens separated by `.`./// Note that `input` isn't validated, and is `str` as ascii is a subset of UTF-8 which is required for any valid keys.pub fn parse_unvalidated(input: &str) -> Option<Key<'_>> {    let (section_name, subsection_or_key) = input.split_once('.')?;    let (subsection_name, value_name) = match subsection_or_key.rsplit_once('.') {        Some((subsection, key)) => (Some(subsection), key),        None => (None, subsection_or_key),    };     Some(Key {        section_name,        subsection_name,        value_name,    })}