def Firsta():
   
    file_dir = '/15 kHz (Noise)/'
    list_of_files = glob.glob('/15 kHz (Noise)/*')
    print(list_of_files)
    asx = str(list_of_files)
    latest_file = max(list_of_files, key=os.path.getctime)
    base = os.path.basename(latest_file)
    print(base)
    file_full = os.path.join(file_dir, base)
    
t1 = Thread(target=Firsta(), args=())
t1.start()
t1.join()

 class Thread(_Verbose):
    """A class that represents a thread of control.
    This class can be safely subclassed in a limited fashion.
    """
    __initialized = False
    # Need to store a reference to sys.exc_info for printing
    # out exceptions when a thread tries to use a global var. during interp.
    # shutdown and thus raises an exception about trying to perform some
    # operation on/with a NoneType
    __exc_info = _sys.exc_info
    # Keep sys.exc_clear too to clear the exception just before
    # allowing .join() to return.
    __exc_clear = _sys.exc_clear
    def __init__(self, group=None, target=None, name=None,
                 args=(), kwargs=None, verbose=None):
        """This constructor should always be called with keyword arguments. Arguments are:
        *group* should be None; reserved for future extension when a ThreadGroup
        class is implemented.
        *target* is the callable object to be invoked by the run()
        method. Defaults to None, meaning nothing is called.
        *name* is the thread name. By default, a unique name is constructed of
        the form "Thread-N" where N is a small decimal number.
        *args* is the argument tuple for the target invocation. Defaults to ().
        *kwargs* is a dictionary of keyword arguments for the target
        invocation. Defaults to {}.
        If a subclass overrides the constructor, it must make sure to invoke
        the base class constructor (Thread.__init__()) before doing anything
        else to the thread.
"""

 t1 = Thread(target=Firsta, args=())

 def fun():
    print('меня вызвали')
    return 'OK'
    
f = fun # f теперь ссылка на функцию
print(f,'\n') # выведет место хранения функции (объекта) в памяти
f_1 = fun() # f_1 ссылка на результат работы функции так как fun() это вызов функции
print(f_1,'\n')
f() # вызываем ф. по ссылке
print(f(),'\n') # вызываем и выводим результат

 import time
def fun():
    print('меня вызвали')
    time.sleep(5)
    print('я закончила работу')
    return 'OK'