def OxmlElement(nsptag_str, attrs=None, nsdecls=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. A dictionary of attribute values may be
    provided as *attrs*; they are set if present. All namespaces defined in
    the dict *nsdecls* are declared in the element using the key as the
    prefix and the value as the namespace name. If *nsdecls* is not provided,
    a single namespace declaration is added based on the prefix on
    *nsptag_str*.
    """
    nsptag = NamespacePrefixedTag(nsptag_str)
    if nsdecls is None:
        nsdecls = nsptag.nsmap
    return oxml_parser.makeelement(
        nsptag.clark_name, attrib=attrs, nsmap=nsdecls
    )