#[macro_export]
macro_rules! hashmap {
    ( $($k:expr => $v:expr),+, ) => { $crate::hashmap!($($k => $v),+) };
    ( $($k:expr => $v:expr),* ) => {
        {
            let mut hm = ::std::collections::HashMap::new();
            $( hm.insert($k, $v); )*
            hm
        }
    };
}