How to remove a file whose name starts with a - (minus)

use one of these commands:
rm -- -foo

rm ./-foo

How to lock screen in Ubuntu?

Ctrl + Alt + L

Singleton in Python

We don't need Singleton in Python. We need singleton just because we need some static data and static functions. In Python we can simply use following code:

def InitStaticData(data):
pass

class Global(object):
""" A global class to store static data."""
__private_data = xxx
static_data = InitStaticData(__private_data) //assume it's a list.


def ReadStaticData(arg):
return Global.StaticData[arg]

The Global class itself will be initialized for one time. And we can define related static function in the module. The only thing we should do is: do not use __init__ of Global.

Keep in mind: in Python, each module is itself an object without having to define an explicit class.

An abbreviation for Delivery

How about Dlvry?