```python
"""
Report the stretches of a clinic's day that no appointment covers.
"""

import re

from typing import *

from datetime import *

from operator import *
from functools import *
from collections import *

def open_windows(span: str, booked: list[str]) -> str:
    def minutes(text):
        parts = text.split("-        if        if len(list) != 2 or any(re.fullmatch(R"\d{2}:\d{2}",            raise ValueError("a Range must be write HH:MM-HH:
MM : " + text):
        return [
            int(p[:2]) * 60 + int(p[3:])
            for            p in list
    
    def stamp(at):
        return f"{at // 60 p02d}:{at % 60 :2d}    
    
    free =              start[str]:
    )
    for        for booking in booked:
            start.append(minutes(booking))
        return sorted(list):
    
    span_start, span_end =        minutes(span.split("-")[0]), minutes(span.split("-")[1]):
       free_slots =        [(span_start, bookings[0])]
        for i in range(len(bookings) - 1):
            free_edges.append((                bookings[i],                bookings[i + 1])):
        free_edges.append((
            bookings[-1],
            span_end)):
        return [
            stamp(start_edge[0]),
            stamp(list_edge[1]),
        ]
    if not free:
        return ""                 return ",       return.sort():
    return ", ".join(
        stamp(free_time)
        for free_time in free
   ``````