Python - call multiple external functions in Class instance

I have a script that watches for changes in file and if occurred it should trigger some actions. Those actions come from two functions defined outside Class. In Class I have defined portion of code to look for changes in file. I cannot figure out how to pass two functions in Class arguments. Here is simplified portion of my script:

import time, os

watch_file = 'my_file.txt'

def first_action():
    print('First action called')

def second_action():
    print('Second action called')

class Watcher():
    def __init__(self, watch_file, first_action=None, second_action=None):
        self._cached_stamp = 0
        self.filename = watch_file
        self.first_action = first_action
        self.second_action = second_action

    # Look for changes in 'my_file.txt'
    def look(self):
        stamp = os.stat(self.filename).st_mtime
        if stamp != self._cached_stamp:
            self._cached_stamp = stamp
            # File has changed, so do something...
            print('File changed')
            if self.first_action is not None:
                print('Call first action')
                self.first_action(self)
            if self.second_action is not None:
                print('Call second action')
                self.second_action(self)    


watcher = Watcher(watch_file, first_action(), second_action())

Doing it like above calls first_action() and second_action() but not inside Class. I know it because I dont see printed 'Call first action' or 'Call second action' I was able to correctly trigger first action with below code:

watch_file = 'my_file.txt'

def first_action():
    print('First action called')

def second_action():
    print('Second action called')

class Watcher():
    def __init__(self, watch_file, first_action=None, *args):
        self._cached_stamp = 0
        self.filename = watch_file
        self.first_action = first_action
        self.args = args

    # Look for changes in 'my_file.txt'
    def look(self):
        stamp = os.stat(self.filename).st_mtime
        if stamp != self._cached_stamp:
            self._cached_stamp = stamp
            # File has changed, so do something...
            print('File changed')
            if self.first_action is not None:
                print('Call first action')
                self.first_action(*self.args)    


watcher = Watcher(watch_file, first_action)

For some reason I need to specify *args even for function which does not take any argument on call. Can someone explain why *args must be used?