from typing import List


def add_line_continuation_characters(command_tokens: List[str]) -> List[str]:
    """
    Add a \\ to the end of each command token that precedes an argument token (starting with -)
    """
    command_tokens = list(command_tokens)  # make a copy

    for i, token in enumerate(command_tokens):
        if i > 0 and token.startswith('-'):
            command_tokens[i-1] += ' \\'

    return command_tokens