def getXMLInteger(elem, tag):
    """
    Return the text within the named tag as an integer.

    Raises an exception if the tag cannot be found or if its textual
    value cannot be converted to an integer.

    Parameters
    ----------

    - elem: the element to search within
    - tag: the name of the tag to look for

    """
    e = elem.find(tag)
    if e is None:
        raise ValueError('Missing %s in %s' % (tag, elem))
    return int(e.text.strip())