Macro metron::impl_unit_from

macro_rules! impl_unit_from {
    ( $unit_into:ty, ( $unit_from:ty =* $factor:literal ) ) => { ... };
    ( $unit_into:ty, ( $unit_from:ty =/ $factor:literal ) ) => { ... };
    ( $unit_into:ty, ( $unit_from:ty => | $num:ident : $num_from:ty| -> $num_out:ty { $conv:expr } ) ) => { ... };
    ( $unit_into:ty, ( $unit_from:ty where N: $num_from_bound:path => | $num:ident $(:N)?| -> $num_out:ty { $conv:expr } ) ) => { ... };
    ( $unit_into:ty, $unit_from:ty =* $factor:literal) => { ... };
    ( $unit_into:ty, $unit_from:ty =/ $factor:literal) => { ... };
    ( $unit_into:ty, $unit_from:ty => | $num:ident : $num_from:ty| -> $num_out:ty { $conv:expr }) => { ... };
    ( $unit_into:ty, $unit_from:ty where N: $num_from_bound:path => | $num:ident $(:N)?| -> $num_out:ty { $conv:expr }) => { ... };
    ( impl $($generics:ident)?, $unit_into:ty, $unit_from:ty, $num_from:ty $(:$num_from_bound:path)?, $num:ident, $num_out:ty, $conv:expr) => { ... };
}