>>> '{:,}'.format(15700000000)
'15,700,000,000'

from string import Template

s = Template("Hi, $name! $name is learning $language")
print(s.substitute(name="Wilber", language="Python"))

d = {"name": "Will", "language": "C#"}
print(s.substitute(d))

# 用$$表示$符号
s = Template("This book ($bname) is 17$$")
print(s.substitute(bname="TCP/IP"))

Hi, Wilber! Wilber is learning Python
Hi, Will! Will is learning C#
This book (TCP/IP) is 17$