An array of size N x M represents pixels of an image.
Each cell of this array contains an array of size 3 with the pixel's color information: `[R,G,B]`
Convert the color image, into an *average* greyscale image. 
The `[R,G,B]` array contains integers between 0 and 255 for each color. 
To transform a color pixel into a greyscale pixel, average the values of that pixel:
```
p = [R,G,B] => [(R+G+B)/3, (R+G+B)/3, (R+G+B)/3]
```
**Note:** the values for the pixel must be integers, therefore you should round floats to the nearest integer.
## Example
Here's an example of a 2x2 image: 
Here's the expected image after transformation:
You are always welcome to check out some of my other katas:
Very Easy (Kyu 8)
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Easy (Kyu 7-6)
Convert Color image to greyscale
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No Ifs No Buts
Medium (Kyu 5-4)
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Hard (Kyu 3-2)
Ascii Art Generator
def color_2_grey(colors):
    return [[[round((r + g + b) / 3)] * 3 for r, g, b in row] for row in colors]
def color_2_grey(colors):
    return [[[round((r + g + b) / 3)] * 3 for r, g, b in row] for row in colors]