Feature request - postfix for f-strings (or other auto-completion)

This is a small qualify of life issue, but one I run into all the time. I start typing my string:

"the value of {variable.name} is {variable.value}"

then realize it has expressions in it, and I need mouse around to put an "f" in front of it. 

Any possibility we could get a postfix for this? i.e., "string".f -> f"string"