Return a 'loose' lxml element having the tag specified by *nsptag_str*.
    *nsptag_str* must contain the standard namespace prefix, e.g. 'a:tbl'.
    The resulting element is an instance of the custom element class for this
    tag name if one is defined.

def OxmlElement(nsptag_str, nsmap=None):
    """
    Return a 'loose' lxml element having the tag specified by *nsptag_str*.
    *nsptag_str* must contain the standard namespace prefix, e.g. 'a:tbl'.
    The resulting element is an instance of the custom element class for this
    tag name if one is defined.
    """
    nsptag = NamespacePrefixedTag(nsptag_str)
    nsmap = nsmap if nsmap is not None else nsptag.nsmap
    return oxml_parser.makeelement(nsptag.clark_name, nsmap=nsmap)