难度大，矩阵下标数不正确

def safe_access(matrix, row, col):
    if 0 <= row < len(matrix) and 0 <= col < len(matrix[0]):
        return matrix[row][col]
    else:
        raise IndexError("Matrix index out of range")

assert 0 <= row < len(matrix), "Row index out of bounds"
assert 0 <= col < len(matrix[0]), "Column index out of bounds"

import numpy as np

matrix = np.array([[1, 2, 3], [4, 5, 6]])
try:
    value = matrix[row, col]
except IndexError as e:
    print(f"Error: {e}")

import unittest

class MatrixTest(unittest.TestCase):
    def test_access(self):
        matrix = [[1, 2], [3, 4]]
        self.assertEqual(safe_access(matrix, 0, 0), 1)
        with self.assertRaises(IndexError):
            safe_access(matrix, 2, 0)