+ /// Sets a required feature bit. Errors if `bit` is outside the feature range as defined
+ /// by [BOLT 9].
+ ///
+ /// Note: Required bits are even. If an odd bit is given, then the corresponding even bit will
+ /// be set instead (i.e., `bit - 1`).
+ ///
+ /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
+ pub fn set_required_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
+ self.set_feature_bit(bit - (bit % 2))
+ }
+
+ /// Sets an optional feature bit. Errors if `bit` is outside the feature range as defined
+ /// by [BOLT 9].
+ ///
+ /// Note: Optional bits are odd. If an even bit is given, then the corresponding odd bit will be
+ /// set instead (i.e., `bit + 1`).
+ ///
+ /// [BOLT 9]: https://github.com/lightning/bolts/blob/master/09-features.md
+ pub fn set_optional_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
+ self.set_feature_bit(bit + (1 - (bit % 2)))
+ }
+
+ fn set_feature_bit(&mut self, bit: usize) -> Result<(), ()> {
+ if bit > 255 {
+ return Err(());
+ }
+ self.set_bit(bit, false)
+ }
+