sets.py 文件源码

def intersection(self, other):
        """Return the intersection of two sets as a new set.

        (I.e. all elements that are in both sets.)
        """
        if not isinstance(other, BaseSet):
            other = Set(other)
        if len(self) <= len(other):
            little, big = self, other
        else:
            little, big = other, self
        common = ifilter(big._data.__contains__, little)
        return self.__class__(common)