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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def newNs(self, href, prefix):
 """Creation of a new Namespace. This function will refuse to create a namespace with a similar prefix than an existing one present on this node. We use href==None in the case of an element creation where the namespace was not defined. """

        ret = libxml2mod.xmlNewNs(self._o, href, prefix)
        if ret is None:raise treeError('xmlNewNs() failed')
        __tmp = xmlNs(_obj=ret)
        return __tmp