minidom美化xml文件格式

关于minidom美化xml文件格式，参考了limodou的这篇文档，
但是有问题，就是每次都多出很多空行，这篇是详细的问题描述和解决思路
我根据思路解决后的代码

#调用例子
#保存xml结果到文件
#遍历nodes，删除所有空格元素
domcopy = domcomm.cloneNode(True)
clearspace(domcopy, domcopy.documentElement)
Indent(domcopy, domcopy.documentElement)
f=file(commfilename,'w')
writer=codecs.lookup('utf-8')[3](f)
domcopy.writexml(writer,encoding='utf-8')
writer.close

def clearspace(dom, node):
    '''
    删除xml文件中的所有空行
    '''
    children = node.childNodes[:]
    if children:
        for nd in children:
            if nd.nodeType == 3 and nd.data.isspace():
                node.removeChild(nd)
            else:
                clearspace(dom,nd)

def Indent(dom, node, indent = 0):
    #这个是原来limodou提供的缩进函数
    # Copy child list because it will change soon
    children = node.childNodes[:]
    # Main node doesn't need to be indented
    if indent:
        text = dom.createTextNode('\n' + '\t' * indent)
        node.parentNode.insertBefore(text, node)
    if children:
        # Append newline after last child, except for text nodes
        if children[-1].nodeType == node.ELEMENT_NODE:
            text = dom.createTextNode('\n' + '\t