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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 get_vcenter(self, **kwargs):
 """ Get vCenter hosts on the switch Args: callback (function):
 A function executed upon completion of the method. Returns: Returns a list of vcenters Raises: None """

        config = ET.Element("config")
        urn = "urn:brocade.com:mgmt:brocade-vswitch"
        ET.SubElement(config, "vcenter", xmlns=urn)
        output = self._callback(config, handler='get_config')
        result = []
        element = ET.fromstring(str(output))
        for vcenter in element.iter('{%s}vcenter'%urn):
            vc = {}
            vc['name'] = vcenter.find('{%s}id' % urn).text
            vc['url'] = (vcenter.find('{%s}credentials' % urn)).find('{%s}url' % urn).text
            isactive = vcenter.find('{%s}activate' %urn)
            if isactive is None:
                vc['isactive'] = False
            else:
                vc['isactive'] = True
            result.append(vc)
        return result