#!/usr/bin/python

import os

path =  os.getcwd()
filenames = os.listdir(path)

for filename in filenames:
    os.rename(filename, filename.replace("jpg", "png").lower())
b1f25abb17827b1c593b233a4dc305d8732fe3af
<mask token>

<mask token>
for filename in filenames:
    os.rename(filename, filename.replace('jpg', 'png').lower())

<mask token>
path = os.getcwd()
filenames = os.listdir(path)
for filename in filenames:
    os.rename(filename, filename.replace('jpg', 'png').lower())

import os
path = os.getcwd()
filenames = os.listdir(path)
for filename in filenames:
    os.rename(filename, filename.replace('jpg', 'png').lower())

#!/usr/bin/python

import os

path =  os.getcwd()
filenames = os.listdir(path)

for filename in filenames:
    os.rename(filename, filename.replace("jpg", "png").lower())