from datetime import datetime


def calc_open_doors(event_date: str):
    """Given event date, calculates the time doors open
    From: https://www.facebook.com/pg/openstudio.bar/about/?ref=page_internal - Open times for venue, not really a doors open policy, just open times
    
    Args:
        event_date (str): Show date in format %Y-%m-%d
    
    Returns:
        str: Doors open time or None if date is invalid
    """
    
    # Create a date object
    try:
        temp_date = datetime.strptime(event_date, '%Y-%m-%d')
    except ValueError:
        return None

    # Open venue so doors open 19:00 on weekday and 13:30 on weekends according to bar facebook page
    if temp_date.weekday() >=5:
        return "7:00 pm"
    else:
        return "1:30 pm"