Function encode 

pub fn encode(param: &ParamType, value: &Value) -> Result<Value, EncodeError>

Marshals an argument value to its TRP wire form, directed by param.

One recursive walk over (type, value). A leaf renders bare at the top level — the resolver coerces it via the param’s flat type — and tagged when it sits inside an aggregate, where the resolver has no element type. Aggregates always render to their tagged structural form. Errors if value’s shape can’t match param.