E2: "The name 'Noise' does not exist in the current context"

[creative10-13]

I have been getting an error: "Assets\Scripts\MapGenerator.cs(14,23): error CS0103: The name 'Noise' does not exist in the current context" after doing ep 2
here is what I have in the line that the error mentioned:

float[,] noiseMap = Noise.GenerateNoiseMap (mapWidth, mapHeight, noiseScale);

I believe that Sebastion was fetching a class from the noise script so is there any way to solve this