def _normalize_idx(self, idx): nidx = idx if nidx < 0: nidx += len(self) if nidx < 0: nidx = 0 return nidx def __getitem__(self, idx): """Implements `x = self[idx]`""" assert(isinstance(idx, int)) nidx = self._normalize_idx(idx) if nidx >= self.length: raise IndexError else: #start at head, skip the NONE sentinel, now at index 0, while loop to walk to nidx, return data # or figure out closer to head or head.prior(tail), make the walk shorter if idx< (self.length/2): #start at head.next, walk forward idx number of nodes current=self.head.next count=0 while count<nidx: current=current.next count+=1 else: #start at head.prior, walk backward len(self.data)-idx-1 number of nodes current=self.head.prior count=self.length-1 while count>nidx: current=current.prior count-=1 return current.val 改写代码风格并保持变量名，代码意思不变

下面是改写后的代码风格：

def _normalize_idx(self, idx):
    nidx = idx
    if nidx < 0:
        nidx += len(self)
        if nidx < 0:
            nidx = 0
    return nidx

def __getitem__(self, idx):
    """Implements `x = self[idx]`"""
    assert(isinstance(idx, int))
    nidx = self._normalize_idx(idx)
    if nidx >= self.length:
        raise IndexError
    else:
        # Start at head, skip the NONE sentinel, now at index 0, while loop to walk to nidx, return data
        # Or figure out closer to head or head.prior(tail), make the walk shorter
        if idx < (self.length/2):    # Start at head.next, walk forward idx number of nodes
            current = self.head.next
            count = 0
            while count < nidx:
                current = current.next
                count += 1
        else:    # Start at head.prior, walk backward len(self.data)-idx-1 number of nodes
            current = self.head.prior
            count = self.length-1
            while count > nidx:
                current = current.prior
                count -= 1
        return current.val

注意，变量名没有改变，只是对代码进行了一些格式化和注释。