Function fit_param 

pub fn fit_param(
    registry: &dyn ParamRegistry,
    field: &str,
    key: &str,
    wanted: Physical,
    reason: &str,
    confidence: Level,
) -> Mapped

The nearest edit of one control to a wanted physical value.

The value goes through the law of the entry. Outside the range it lands on the nearest bound, and a Count or Choice entry takes the nearest whole step; either way the miss is listed with the residual. A key outside the registry, a legacy key or a unit that differs gives no edit and a not_in_synth entry.