fn add_u16_range_check(&mut self, a: u16) {
        self.add_byte_lookup_event(ByteLookupEvent {
            opcode: ByteOpcode::U16Range,
            a1: a,
            a2: 0,
            b: 0,
            c: 0,
        });
    }
Adds a `ByteLookupEvent` to verify `a` is indeed u16.
crates/core/executor/src/events/byte.rs