Indents the inputted XML element based on the given indent level.
    
    :param      elem    | <xml.etree.Element>

def xmlindent(elem, level=0, spacer='  '):
    """
    Indents the inputted XML element based on the given indent level.
    
    :param      elem    | <xml.etree.Element>
    """
    i = "\n" + level * spacer
    if len(elem):
        if not elem.text or not elem.text.strip():
            elem.text = i + spacer
        if not elem.tail or not elem.tail.strip():
            elem.tail = i
        for elem in elem:
            xmlindent(elem, level + 1)
        if not elem.tail or not elem.tail.strip():
            elem.tail = i
    else:
        if level and (not elem.tail or not elem.tail.strip()):
            elem.tail = i