[Tutor] Faster procedure to filter two lists . Please help

[Tim Peters]

[Alan Gauld]
> OK, The timbot's word is good enough for me, I won't bother
> looking at the code, I'll revert to my previous assumption! :-)

It's educational to look at the code anyway <wink>.  Here it is, from
Python's listobject.c:

static int
list_length(PyListObject *a)
{
	return a->ob_size;
}

People shouldn't be afraid to look at C code -- it won't bite them,
and it's often the easiest way to get a definitive answer about the
implementation.  OTOH, people should be afraid to _write_ C code:  it
will bite you every time <0.9 wink>.