Function convert 

pub fn convert<T, U>(x: T) -> U

Arbitrary bitvector-to-bitvector conversion. Either truncates or zero-extends depending on the relative sizes of T and U. Both T and U must be represented as bitvectors (BVType) at the Crucible level, which is the case for both Bv and primitive integer types. (Note that this still zero-extends when used on signed integers: convert::<i8, i16>(-1) return 255, not -1.)