Exercises

7.1 — Write a program, save_load.py, that opens a file in append mode and adds a timestamped line to the file. When the program starts, it reads the contents of the file and prints them. Then, it repetitively prompts the user to enter a line of text, writes the line and a timestamp to the file and asks the user if they want to continue.

7.2 — Write a program, count_lines.py, that takes a filename as a command line argument, and prints the number of lines, words, and characters (similar to Unix utility wc).

7.3 — Write a program, todo.py, a task management utility that remembers your tasks between runs by saving them to a file.

Spec.

• Tasks are stored in tasks.json as a list of tuples, each like ("buy milk", false).
• On start, load the tasks (empty list if the file doesn't exist)
• Support these commands (via a menu loop):
  • add <text> — add a new task (not done).
  • list — show all tasks, numbered, with [x]/[ ] for done/not-done.
  • done <n> — mark task n as done.
  • remove <n> — delete task n.
  • quit — exit.
• Save to tasks.json after any change, so the list persists.
• Decompose into functions: load_tasks, save_tasks, add_task, mark_done, remove_task, show_tasks, and a main() that coordinates everything.