'clearw(addr, ndx = 0) -> int
Clears word at ``((uint16_t*)addr)[ndx]`` from the cache and
returns the removed value or `None` if the address was not completely set.
Examples:
>>> l = MemLeak(lambda a: None)
>>> l.cache = {0:\'a\', 1: \'b\'}
>>> l.n(0, 2) == \'ab\'
True
>>> l.clearw(0) == unpack(\'ab\', 16)
True
>>> l.cache'

def clearw(self, addr, ndx=0):

    return self._clear(addr, ndx, 2)
