code: def matrix_mult(a, b):
      """a = a * b
      Matrices (2x2 matrix) Multiplication method used for the next solutions.
      The result of multiplication is saved in 'a' (because of that, the reference
      shouldn't be changed, only change the values after all computations are completed
      because 'b' could be the same reference/matrix as 'a').
      a[0] is the first row of a, which contains a[0][0], a[0][1]
      Python "unrolls" a00, a01 = a[0], which effectively makes it:
      a00 = a[0][0] and a01 = a[0][1]
      """
      a00, a01 = a[0]
      a10, a11 = a[1]
      b00, b01 = b[0]
      b10, b11 = b[1]
      a[0][0] = a00 * b00 + a01 * b10
      a[0][1] = a00 * b01 + a01 * b11
      a[1][0] = a10 * b00 + a11 * b10
      a[1][1] = a10 * b01 + a11 * b11
  
file_path: coding-problems/Other/nth_fibonacci_number.py
imports: import math
label_desc: Use image node_id 5 for calling a global function with example usage: matrix_mult(a, b) without return types