input: Write a function to perform matrix multiplication on two given matrices A and B. The function should ensure that the number of columns in matrix A is equal to the number of rows in matrix B. If the matrices are not compatible for multiplication, the function should return an error message. Otherwise, it should return the resulting matrix.
  assert matrix_multiplication([[1, 2], [3, 4]], [[1, 0], [0, 1]])==[[1, 2], [3, 4]]
  assert matrix_multiplication([[1, 2]], [[5], [6]])==[[17]]
  assert matrix_multiplication([[1, 2, 3], [4, 5, 6]], [[7, 8], [9, 10], [11, 12]])==[[58, 64], [139, 154]]
  assert matrix_multiplication([[1, 2]], [[1, 2, 3], [4, 5, 6]])=='Error: The matrices cannot be multiplied'
  assert matrix_multiplication([[1]], [[2]])==[[2]]
output: def matrix_multiplication(A, B):
      if len(A[0]) != len(B):
          return 'Error: The matrices cannot be multiplied'
      result = [[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)):
                  result[i][j] += A[i][k] * B[k][j]
      return result