f-Strings provide a concise and convenient way to embed Python expressions inside string literals for formatting.
The f or F prefix before the string indicates that it is an f-string.
The string itself can be formatted in much the same way that you would with str.format().
>>> name = 'Fred'
>>> f"He said his name is {name}."
'He said his name is Fred.'
>>> "He said his name is {name}.".format(name=name)
'He said his name is Fred.'Expressions
You can put any valid Python expression inside the braces and it will be evaluated and formatted.
>>> f"{2 * 37}"
'74'
>>> f"{name.lower()}"
'fred'Callables
You can call any callable Python object inside the braces and it will be evaluated and formatted.
>>> def to_lowercase(input):
... return input.lower()
...
>>> name = "Eric Idle"
>>> f"{to_lowercase(name)} is funny."
'eric idle is funny.'