FixedWithInteger.swift

extension FixedWidthInteger {
    
    public init<C: Collection>(littleEndianBytes bytes: C) where C.Element == UInt8 {
        let (quotient, remainder) = Self.bitWidth.quotientAndRemainder(dividingBy: 8)
        precondition(bytes.count == (quotient + remainder.signum())
        var iterator = bytes.makeIterator()
        self.init(littleEndianBytes: &iterator)
    }
    
    public init<I: IteratorProtocol>(littleEndianBytes iterator: inout I) where I.Element == UInt8 {
        self = stride(from: 0, to: Self.bitWidth, by: 8).reduce(into: 0) {
            $0 |= Self(truncatingIfNeeded: iterator.next()!) &<< $1
        }
    }
}