Macro declare_inference_label 

macro_rules! declare_inference_label {
    ($name:ident) => { ... };
    ($name:ident, $label:expr) => { ... };
    (@impl_trait $name:ident, $label:expr) => { ... };
}

Conveniently creates InferenceLabel for use in a propagator.

In case it is desirable, the exact string that is printed in the DRCP proof can be provided as a second parameter. Otherwise, the type name is converted to snake

Example

declare_inference_label!(SomeInference);
declare_inference_label!(OtherInference, "label");

// Now we can use `SomeInference` and `OtherInference` when creating an inference
// code as it implements `InferenceLabel`.

case.