input: Write a function to multiply two matrices, A and B, and return the resulting matrix C. If the matrices are not compatible for multiplication, return "Matrix multiplication not possible".
  def matrix_mult(A, B):
      if len(A[0]) != len(B):
          return "Matrix multiplication not possible"
      
      C = [[0 for _ in range(len(B[0]))] for _ in range(len(A))]
      
      for i in range(len(A)):
          for j in range(len(B[0])):
              for k in range(len(B)):
                  C[i][j] += A[i][k] * B[k][j]
                  
      return C
  
  assert matrix_mult([[3, 4], [1, 2]], [[7, 5], [0, 1]]) == [[21, 17], [0, 2]]
  assert matrix_mult([[1, 2], [3, 4]], [[5, 6], [7, 8]]) == [[19, 22], [43, 50]]
  assert matrix_mult([[1, 2]], [[3], [4]]) == [[11]]
  assert matrix_mult([[1, 2, 3]], [[4], [5], [6]]) == [[32]]
  assert matrix_mult([[1, 2], [3, 4]], [[1]]) == "Matrix multiplication not possible"
output: def matrix_mult(A, B):
      if len(A[0]) != len(B):
          return "Matrix multiplication not possible"
      
      C = [[0 for _ in range(len(B[0]))] for _ in range(len(A))]
      
      for i in range(len(A)):
          for j in range(len(B[0])):
              for k in range(len(B)):
                  C[i][j] += A[i][k] * B[k][j]
                  
      return C