Function with matrix : I dont know how to start. What should be arg reshape or.... ?
function that multiplies by -1 numbers in a matrix with an odd sum of the 

    index? 
>I noticed that after expanding the matrix into a list, every second word should be multiplied by -1.
>help pls 

>thanks
>`enter code here`example

    [[[ 0  1  2]
      [ 3  4  5]
      [ 6  7  8]]
    
     [[ 9 10 11]
      [12 13 14]
      [15 16 17]]
    
     [[18 19 20]
      [21 22 23]
      [24 25 26]]]
    
        [[[ 0  -1  2]
          [ -3  4  -5]
          [ 6  -7  8]]
    
         [[ -9 10 -11]
          [12 -13 14]
          [-15 16 -17]]
    
         [[18 -19 20]
          [-21 22 -23]
          [24 -25 26]]]
         

