Python properties have overgrown code
I am looking at this code (from https://github.com/kaitai-io/kaitai_struct/issues/367) and thinking "cant this be simpler"?
```py
@property
def num2(self):
    if hasattr(self, '_m_num2'):
        return self._m_num2 if hasattr(self, '_m_num2') else None

    self._m_num2 = ((self.num2_hi << 16) | self.num2_lo)
    return self._m_num2 if hasattr(self, '_m_num2') else None
```
I think this would be just fine:
```py
@property
def num2(self):
    if hasattr(self, '_m_num2'):
        return self._m_num2

    self._m_num2 = ((self.num2_hi << 16) | self.num2_lo)
    return self._m_num2
```
