def METHOD_NAME(xml_list):
    """
    Iterates through XML list, shows an error if an XML file is not an XML file or does not exist.
    A list of valid XML files is returned (Not valid files are thrown out)
    """
    out_list = []
    for xml_path in xml_list:
        if os.path.isfile(xml_path):
            out_list.append(xml_path)
        else:
            print(
                "WARNING: XML {} is not a valid file. Rejecting file.".format(xml_path)
            )
    return out_list