'Refit namespace qualification by replacing prefixes
with explicit namespaces. Also purges prefix mapping table.
@return: self
@rtype: L{Element}'

def refitPrefixes(self):

    for c in self.children:
        c.refitPrefixes()
    if (self.prefix is not None):
        ns = self.resolvePrefix(self.prefix)
        if (ns[1] is not None):
            self.expns = ns[1]
    self.prefix = None
    self.nsprefixes = {}
    return self
