let n = 1;
f"f-strings can be {
  let n = n + 1;
  f"nested arbitrarily. {
    let n = n + 1;
    f"This one is at depth {n},"
  } this one at depth {n},"
} and this one at depth {n}."

# output:
"f-strings can be nested arbitrarily. This one is at depth 3, this one at depth 2, and this one at depth 1."