     /// Returns the `UInt8`-value of the next 4 bit and
     /// increments the reading cursor by 4 bits.
     public mutating func readNibble() throws -> UInt8 {
-        return UInt8(try readBits(quantitiy: 4))
+        let bitsPerNibble = 4
+        return UInt8(try readBits(quantitiy: bitsPerNibble))
     }
     
     // MARK: - Find

            throw BinaryError.outOfBounds
        }
        let byteCursor = index / byteSize
        let bitindex = 7 - (index % byteSize)
        return (bytesStore[byteCursor] >> bitindex) & 1
    }
    

    
    /// Initialize with a `String` of hexadecimal values.
    public init?(hexString: String) {
        let charsPerByte = 2
        let hexBase = 16
        let bytes = hexString.chunked(by: charsPerByte).compactMap{ UInt8($0, radix: hexBase) }
        guard hexString.count / charsPerByte == bytes.count else {
            return nil
        }
        self.init(bytes: bytes)
