def METHOD_NAME(doc):
    """
    transform:
    [corpora][conc_calc_backend conf="..."]...
    into:
    [global][calc_backend conf="..."]...
    """
    src_elm = doc.find('corpora/conc_calc_backend')
    dst_elm = doc.find('global')
    if src_elm is not None and dst_elm is not None:
        print((src_elm.attrib['conf']))
        new_elm = etree.SubElement(dst_elm, 'calc_backend')
        new_elm.attrib['conf'] = src_elm.attrib['conf']
        new_elm.text = src_elm.text
        remove_element(src_elm)
    else:
        raise Exception('problem finding "corpora/conc_calc_backend" or "global" elements')