Macro hobo_css::animation_timing_function

macro_rules! animation_timing_function {
    (initial) => { ... };
    (inherit) => { ... };
    (unset) => { ... };
    (linear) => { ... };
    (ease) => { ... };
    (ease - in) => { ... };
    (ease - out) => { ... };
    (ease - in - out) => { ... };
    (step - start) => { ... };
    (step - end) => { ... };
    ($str:expr) => { ... };
}