def write(scope, filename, lines, mode=['a']):
    """
    Writes the given string into the given file.
    The following modes are supported:

      - 'a': Append to the file if it already exists.
      - 'w': Replace the file if it already exists.

    :type  filename: string
    :param filename: A filename.
    :type  lines: string
    :param lines: The data that is written into the file.
    :type  mode: string
    :param mode: Any of the above listed modes.
    """
    with open(filename[0], mode[0]) as fp:
        fp.writelines(['%s\n' % line.rstrip() for line in lines])
    return True