System.Drawing.PixelData.this C# (CSharp) Method

        public unsafe byte this[int channel]
        {
            get {
                if (channel < 0 || channel > 2)
                    throw new ArgumentOutOfRangeException("channel", channel, "valid range is [0,3]");

                fixed (byte *p = &B)
                    return p[channel];
            }
            set {
                if (channel < 0 || channel > 2)
                    throw new ArgumentOutOfRangeException("channel", channel, "valid range is [0,3]");

                fixed (byte *p = &B)
                    p[channel] = value;
            }
        }