def float_list_input(prompt="", stop_words=("stop", "end", "halt")):
    """Uses `input(prompt)` to request a list of float values from the user, retrying if the user
    does not enter a valid value. The user can terminate the entry loop by entering one of the `stop_words`,
    which are "stop", "end" and "halt" by default.

     @param str prompt: The prompt to display.
     @return float: The entered value.
    """
    floats = []

    while True:
        try:
            string = input(prompt).strip()
            if not len(string):
                continue
            if string.lower() in stop_words:
                return floats

            floats.append(float(string))
        except ValueError:
            print("Invalid input. Please enter a float value.")