Macro dilib::get_singleton

macro_rules! get_singleton {
    ($singleton_type:ty) => { ... };
    ($singleton_type:ty, $name:expr) => { ... };
    (trait $trait_type:ident $(<$($generic:ident),+>)?) => { ... };
    (trait $trait_type:ident $(<$($generic:ident),+>)?, $name:expr) => { ... };
}

Returns a singleton value from the global Container or None if is not in the container.