Debug thingy imagined by @waffle-annie brought to life!

example.py

from waffle_debug import debug


debug("The answer is {x}!") @ 6  # debug at line 6
x = int(input("3 + 3 = "))
x = 6

waffle_debug.py

import inspect
import sys
from string import Formatter
from types import FrameType
from typing import Any


class debug:
	def __init__(self, value: str) -> None:
		self.__value = value

		if (cur_frame := inspect.currentframe()) is None or (
			prev_frame := cur_frame.f_back
		) is None:
			raise RuntimeError

		self.__debugframe = prev_frame
		self.__line_number = -1

	def __matmul__(self, line_number: int) -> None:
		if line_number <= 0:
			raise ValueError("line number must be positive")

		self.__line_number = line_number

		def trace_func(frame: FrameType, event: str, arg: Any) -> None:
			formatter = Formatter()
			if frame.f_lineno == self.__line_number and event == "return":
				args_required = [
					arg[1] for arg in formatter.parse(self.__value) if arg[1] is not None
				]
				args_given = {
					key: value for key, value in frame.f_locals.items() if key in args_required
				}
				if len(args_required) != len(args_given):
					raise NameError("some variables are not defined")

				print(formatter.vformat(self.__value, [], args_given))

		self.__debugframe.f_trace = trace_func

		sys.settrace(trace_func)