def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def linear_search(lst,size,value):
    i = 0
    while i < size:
        if lst[i] == value:
            return i
        i = i + 1
    return -1