def _walkto(self, walkto):
    rev = self._walkfrom
    cs = self._children
    roots = self._roots
    idx = self._revlog.index
    while (rev >= walkto):
        data = idx[rev]
        isroot = True
        for prev in [data[5], data[6]]:
            if (prev != nullrev):
                cs.setdefault(prev, []).append(rev)
                isroot = False
        if isroot:
            roots.append(rev)
        rev -= 1
    self._walkfrom = rev
def _walkto(self, walkto):
    rev = self._walkfrom
    cs = self._children
    roots = self._roots
    idx = self._revlog.index
    while (rev >= walkto):
        data = idx[rev]
        isroot = True
        for prev in [data[5], data[6]]:
            if (prev != nullrev):
                cs.setdefault(prev, []).append(rev)
                isroot = False
        if isroot:
            roots.append(rev)
        rev -= 1
    self._walkfrom = rev