def strip_repl_characters(code):
    """Removes the first four characters from each REPL-style line.

    >>> strip_repl_characters('>>> "banana"') == '"banana"'
    True
    >>> strip_repl_characters('... banana') == 'banana'
    True
    """
    stripped_lines = []
    for line in code.splitlines():
        if line.startswith('>>> ') or line.startswith('... '):
            stripped_lines.append(line[4:])
        else:
            stripped_lines.append(line)
    return '\n'.join(stripped_lines)