Specialized-purpose timer #1 : It can adjust "from-to duration" and when exit the program, returns the recent-counting and accumulated time.

specialized_timer_1.py

#!/usr/bin/python3
import time
start=time.time()
end=time.time()
latency=end-start
import signal,subprocess,sys,threading,os,random
def is_str_is_integer(string):
	if string[0]=='-':
		n=1
	else: n=0
	for char in string[n:]:
		if char in ['0','1','2','3','4','5','6','7','8','9']: continue
		else: return False
	return True
def sec_to_hms(sec):
	tmp=sec%3600
	result=[None,None,None]
	result[0]=int(sec//3600)
	result[1]=int(tmp//60)
	result[2]=round(tmp%60)
	return result
def endProg(signum,frame):
	global Is_SIGTERM_Handler_Running
	if not Is_SIGTERM_Handler_Running: Is_SIGTERM_Handler_Running=True
	else: return
	end=time.time()
	print()
	new_duration=(end-start-latency)
	total_duration=new_duration+from_[0]*3600+from_[1]*60+from_[2]
	result=sec_to_hms(new_duration)
	print('New Time used :',':'.join(map(str,result)))
	result=sec_to_hms(total_duration)
	print('Total Time used :',':'.join(map(str,result)))
	exit()
def sndAlert():
	for i in range(3):
		print('\a',end='',flush=True)
		time.sleep(0.75)
	# Playing song as ringtone for alerting
	while True:
		subprocess.run(executable='mplayer',args=['mplayer','-speed',str(random.randint(5,20)/10),'/home/np-chaonay/Music/Created/Auld-Lang-Syne_Gay-Gordon_Remix_YouTube-from-darrin42.flac'],stdout=subprocess.DEVNULL,stderr=subprocess.DEVNULL,stdin=subprocess.DEVNULL)

try: to=sys.argv[1]
except Exception: to='0:50:0'
try: from_=sys.argv[2]
except Exception: from_='0:0:0'
if to in ['','.']: to='0:50:0'
if from_ in ['','.']: from_='0:0:0'

diff=[None,None,None]
to=to.split(':')
from_=from_.split(':')

if len(to)!=3 or len(from_)!=3: raise ValueError('Inputted arguments should be in format "<H>:<M>:<S>".')
for num in to:
	if not is_str_is_integer(num): raise ValueError('Inputted arguments should be in format "<H>:<M>:<S>".')
for num in from_:
	if not is_str_is_integer(num): raise ValueError('Inputted arguments should be in format "<H>:<M>:<S>".')

to=list(map(int,to))
from_=list(map(int,from_))

for num in to:
	if num<0: raise ValueError('Inputted arguments should be positive or zero.')
for num in from_:
	if num<0: raise ValueError('Inputted arguments should be positive or zero.')

diff[0]=int(to[0])-int(from_[0])
diff[1]=int(to[1])-int(from_[1])
diff[2]=int(to[2])-int(from_[2])
diff_sec=diff[0]*3600+diff[1]*60+diff[2]

os.environ['PULSE_PROP']='media.role=userh'
Is_SIGTERM_Handler_Running=False
signal.signal(signal.SIGINT,endProg)
Thread1=threading.Thread(target=print,args=['Timer has passed the specific duration.'],daemon=True)
Thread2=threading.Thread(target=sndAlert,daemon=True)
# Sending GUI notification
Thread3=threading.Thread(target=subprocess.run,kwargs={'executable':'notify-send','args':['notify-send','-i','/usr/share/icons/Humanity/apps/22/clock.svg','Specialized Timer','Timer has passed the specific duration.'],'stdout':subprocess.DEVNULL,'stderr':subprocess.DEVNULL,'stdin':subprocess.DEVNULL},daemon=True)

print('Count from :',':'.join(map(str,from_)))
print('Count To :',':'.join(map(str,to)))

while True:
	end=time.time()
	if end-start>=(diff_sec):
		Thread1.start(); Thread2.start(); Thread3.start()
		break
	else:
		try: time.sleep((diff_sec-(end-start))/2)
		except Exception: continue
while True:
	time.sleep(900)