Add imports for 128-bit Bounded

src/bounds.rs

@@ -2,6 +2,8 @@ use core::{usize, u8, u16, u32, u64};
 use core::{isize, i8, i16, i32, i64};
 use core::{f32, f64};
 use core::num::Wrapping;
+#[cfg(feature = "i128")]
+use core::{i128, u128};
 
 /// Numbers which have upper and lower bounds
 pub trait Bounded {