python string.format

 https://stackoverflow.com/questions/3404245/string-formatting-django

A better, more modern approach might be that of https://www.w3schools.com/python/ref_string_format.asp

txt = "For only {price:.2f} dollars!"
print(txt.format(price = 49))

or better yet:

txt1 = "My name is {fname}, I'm {age}".format(fname = "John", age = 36)
txt2 = "My name is {0}, I'm {1}".format("John",36)
txt3 = "My name is {}, I'm {}".format("John",36)