human
argarse custom action.
assistant
Here is a Python function to create custom action

import argparse

def parse_custom_action(action):
    """
    Parse custom action
    """
    if action == 'up':
        return 0
    elif action == 'down':
        return 1
    elif action == 'left':
        return 2
    elif action == 'right':
        return 3
    elif action =='stop':
        return 4
    else:
        return -1

# Enter the action
action = 'up'

# Calling the function
print((parse_custom_action(action)))

#Example Output
# 0

#Remember to inspect code for bugs.