```
class Solution(object):
def generateParenthesis(self, n):
"""
:type n: int
:rtype: List[str]
"""
return ['(' + litem + ')' + ritem for i in range(n) for litem in self.generateParenthesis(i) for ritem in self.generateParenthesis(n-1-i)] or ['']
```

Format the last line a little to make it easy to read

```
return ['(' + litem + ')' + ritem \
for i in range(n) \
for litem in self.generateParenthesis(i) \
for ritem in self.generateParenthesis(n-1-i)] \
or ['']
```