def _read_file(script):
    """ Function to load either a script file or list.

    Arguments
    ---------
    script: str/str
        Either a file to read, or a list of strings to use.

    Returns
    -------
        List of strings where each element is one command.
    """
    if script is None:
        return ""
    with open(script, "r") as f:
        script_string = f.read()
    return script_string