     ///
     /// - Parameter data: The Data struct to fill from data in the buffer
     ///
-    /// - Returns:
+    /// - Returns: The number of bytes actually copied from the buffer. It will be equal
+    ///           to the number of bytes lect in the buffer.
     public func fill(data: inout Data) -> Int {
         
         let result = localData.length - byteIndex


// MARK: BufferList 

public class BufferList {

    // MARK: -- Private 
    
    /// Internal storage buffer
    private let localData = NSMutableData()
    
    /// Byte offset inside of internal storage buffer
    private var byteIndex = 0

    ///
    /// - Parameter data: The NSMutableData object to fill from data in the buffer
    ///
    /// - Returns: The number of bytes actually copied from the buffer. It will be equal
    ///           to the number of bytes lect in the buffer.
    public func fill(data: NSMutableData) -> Int {
        
        let result = localData.length - byteIndex
