def merge_xml(xmls,output_file):
    """
    merge xml files

    Parameters:
    -----------
    xmls: list
        List of paths of the xml files
    output_file: str
        Path of the merged xml
    """
    if len(xmls) <2 :
        raise Exception("Need two or more xml files to merge")

    xmls = " ".join(xmls)

    msg = f"scxmlmerge {xmls} > {output_file}"

    # os.system(msg)
    return msg