Macro null_propagate_reverse 

macro_rules! null_propagate_reverse {
    ($value:expr, $output_constraint:expr) => { ... };
}

Macro for null handling in reverse evaluation. If the constant value is NULL:

• If output constraint is Equals(Value::Null), return Universal (any input could produce NULL)
• Otherwise, return Empty (non-NULL output is impossible with NULL input)

Usage: let value = null_propagate_reverse!(constant_value, output_constraint);