input: Write a function to multiply two matrices A and B to produce a matrix C where each element is the product of the corresponding elements of A and B. If the number of columns in A is not equal to the number of rows in B, return "Matrix multiplication not possible".
  assert matrixMultiplication([[3, 4], [1, 2]], [[7, 5], [0, 1]])==[[21, 20], [0, 2]]
  assert matrixMultiplication([[3, 4], [1, 2]], [[7, 5, 6], [0, 1, 2]])=="Matrix multiplication not possible"
  assert matrixMultiplication([], [])==[]
  assert matrixMultiplication([[1, 2], [3, 4]], [[2, 3], [4, 5]])==[[10, 13], [22, 29]]
  assert matrixMultiplication([[5]], [[3]])==[[15]]
output: def matrixMultiplication(A, B):
      if len(A) == 0 or len(B) == 0:
          return []
      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