         return format(UInt64(count), sourceUnit: sourceUnit, targetUnitType: targetUnitType, formatter: formatter)
     }
     
-    static func format(count: UInt, sourceUnit: BitUnit = .Bit, targetUnitType: BitUnitType = .DecimalBitUnit, formatter: NSNumberFormatter = defaultFormatter) -> String? {
-        guard count >= 0 else {
-            return nil
-        }
+    static func format(count: UInt, sourceUnit: BitUnit = .Bit, targetUnitType: BitUnitType = .DecimalBitUnit, formatter: NSNumberFormatter = defaultFormatter) -> String {
         return format(UInt64(count), sourceUnit: sourceUnit, targetUnitType: targetUnitType, formatter: formatter)
     }
     

    }

}


        return convert(UInt64(count), from: from, to: to)
    }
    
    static func convert(count: UInt, from: BitUnit, to: BitUnit) -> UInt64 {
        return convert(UInt64(count), from: from, to: to)
    }
    
