input: Write a python function to multiply two matrices.
  assert multiply_matrices([[1, 2], [3, 4]], [[5, 6], [7, 8]]) == [[19, 22], [43, 50]]
  assert multiply_matrices([[2, 0], [1, 2]], [[1, 2], [3, 4]]) == [[2, 4], [7, 10]]
  assert multiply_matrices([[1, 1, 1], [1, 1, 1]], [[1, 2], [3, 4], [5, 6]]) == [[9, 12], [9, 12]]
output: def multiply_matrices(matrix1, matrix2):
      result = [[0 for _ in range(len(matrix2[0]))] for _ in range(len(matrix1))]
      
      for i in range(len(matrix1)):
          for j in range(len(matrix2[0])):
              for k in range(len(matrix2)):
                  result[i][j] += matrix1[i][k] * matrix2[k][j]
                  
      return result