def send_out(**kwargs):
    result = ''
    if kwargs:
        result = '?' + '&'.join(f'{k}={v}' for k, v in kwargs.items())
    return result


query_str = send_out(limit=1, start=1)
print(query_str)
query_str = send_out(start=1)
print(query_str)
query_str = send_out()
print(query_str)
#r = requests.get('https://hui' + query_str)