'Set the machine type of the stopped instance. Can be the short-name,
a full, or partial URL.
:param  node: Target node object to change
:type   node: :class:`Node`
:param  machine_type: Desired machine type
:type   machine_type: ``str``
:return:  True if successful
:rtype:   ``bool``'

def ex_set_machine_type(self, node, machine_type='n1-standard-1'):

    request = mt_url = ('/zones/%s' % node.extra['zone'].name)
    mt = machine_type.split('/')[(-1)]
    mt_url = ('%s/machineTypes/%s' % (mt_url, mt))
    request = ('%s/instances/%s/setMachineType' % (request, node.name))
    body = {'machineType': mt_url}
    self.connection.async_request(request, method='POST', data=body)
    return True
