只要是可以for的object，都可以用tqdm监测循环遍历（ interate）的进度。
class tqdm():
"""
Decorate an iterable object, returning an iterator which acts exactly like the original iterable, but prints a dynamically updating progressbar every time a value is requested.
"""
@envwrap("TQDM_") # override defaults via env vars
def __init__(self, iterable=None, desc=None, total=None, leave=True,
file=None, ncols=None, mininterval=0.1,
maxinterval=10.0, miniters=None, ascii=None, disable=False,
unit='it', unit_scale=False, dynamic_ncols=False,
smoothing=0.3, bar_format=None, initial=0, position=None,
postfix=None, unit_divisor=1000, write_bytes=False,
lock_args=None, nrows=None, colour=None, delay=0):
