'Return XML for a [Content_Types].xml based on items in *entries*.'

def _xml_from(self, entries):

    types_bldr = a_Types().with_nsdecls()
    for entry in entries:
        if (entry[0] == u'Default'):
            (ext, content_type) = entry[1:]
            default_bldr = a_Default()
            default_bldr.with_Extension(ext)
            default_bldr.with_ContentType(content_type)
            types_bldr.with_child(default_bldr)
        elif (entry[0] == u'Override'):
            (partname, content_type) = entry[1:]
            override_bldr = an_Override()
            override_bldr.with_PartName(partname)
            override_bldr.with_ContentType(content_type)
            types_bldr.with_child(override_bldr)
    return types_bldr.xml()
