Reset sorted list load.

        The *load* specifies the load-factor of the list. The default load
        factor of '1000' works well for lists from tens to tens of millions of
        elements.  Good practice is to use a value that is the cube root of the
        list size.  With billions of elements, the best load factor depends on
        your usage.  It's best to leave the load factor at the default until
        you start benchmarking.

def _reset(self, load):
        """
        Reset sorted list load.

        The *load* specifies the load-factor of the list. The default load
        factor of '1000' works well for lists from tens to tens of millions of
        elements.  Good practice is to use a value that is the cube root of the
        list size.  With billions of elements, the best load factor depends on
        your usage.  It's best to leave the load factor at the default until
        you start benchmarking.
        """
        values = reduce(iadd, self._lists, [])
        self._clear()
        self._load = load
        self._half = load >> 1
        self._dual = load << 1
        self._update(values)