import re


def calc_open_doors(descr: str):
    """Given event description, searches for the time doors open
    
    Args:
        descr (str): Show description to search
    
    Returns:
        str: Doors open time or "" if date is invalid
    """
    
    # Doors open calculate from the description
    #doors_open = re.search("[^\n.|\-,\\/]*doors[^\n.|\-,\\/]*",descr,re.I)
    doors_open_1 = re.search("doors[\s\D]*(\d+:*\d*(am|pm)?)",descr,re.I)
    #doors_open_2 = re.search("\d+:*\d*(am|pm)?[\s\S]*doors",descr,re.I)
    if doors_open_1:
        return doors_open_1.group(1).strip()
    else:
        return None