给定两个字符串，编写一个Python函数来检查它们是否是相互旋转。
字符串1： 'hello'
字符串2:  'lohel'
可以将字符串1复制一份并拼接，判断字符串2是否是这个新字符串的子串。如果是，那么字符串1和字符串2就是相互旋转的。

示例代码：

```python
def is_rotation(s1, s2):
    if len(s1) != len(s2):
        return False
    s1s1 = s1 + s1
    if s2 in s1s1:
        return True
    else:
        return False
```

调用函数：

```python
s1 = 'hello'
s2 = 'lohel'
if is_rotation(s1, s2):
    print(f"{s1} and {s2} are rotated versions of each other")
else:
    print(f"{s1} and {s2} are not rotated versions of each other")
```

输出结果：

```
hello and lohel are rotated versions of each other
```