from tqdm import tqdm
from time import sleep

with tqdm(total=4, desc='1st loop', position=2) as pbar1:
    with tqdm(total=5, desc='2nd loop', position=1) as pbar2:
        with tqdm(total=50, desc='3rd loop', position=0) as pbar3:

            for i in range(4):
                pbar2.reset()
                for j in range(5): 
                    pbar3.reset()
                    for k in range(50):
                        pbar3.update(1)
                        sleep(0.01)
                    pbar2.update(1)
                pbar1.update(1)