import operator


def get_pub_front_door(building_coords):
    """
    Gets the co-ordinates just outside the front door (south-west corner) of
    the pub.

    Parameters
    ----------
    building_coords : dict
        Keys are the buildings' numbers (or "pub" for the pub) and the values 
        are lists of all co-ordinates that are within the building.

    Returns
    -------
    front_door_coords : tuple
        A length 2 tuple giving the (x,y) co-ordinates of the pub's front door.

    """
    # Set front door coords to be outside bottom left corner of pub
    front_door_y = min(building_coords["pub"], 
                       key = operator.itemgetter(1))[1] - 1
    front_door_x = min(building_coords["pub"], 
                       key = operator.itemgetter(0))[0] - 1
    
    front_door_coords = (front_door_x, front_door_y)
    
    return front_door_coords