code: def upgrade_plan(self, subid, vpsplanid, params=None):
          ''' /v1/server/upgrade_plan
          POST - account
          Upgrade the plan of a virtual machine. The virtual machine will be
          rebooted upon a successful upgrade.
  
          Link: https://www.vultr.com/api/#server_upgrade_plan
          '''
          params = update_params(params, {
              'SUBID': subid,
              'VPSPLANID': vpsplanid
          })
          return self.request('/v1/server/upgrade_plan', params, 'POST'f upgrade_plan(self, subid, vpsplanid, params=None):
          ''' /v1/server/upgrade_plan
          POST - account
          Upgrade the plan of a virtual machine. The virtual machine will be
          rebooted upon a successful upgrade.
  
          Link: https://www.vultr.com/api/#server_upgrade_plan
          '''
          params = update_params(params, {
              'SUBID': subid,
              'VPSPLANID': vpsplanid
          })
          return self.request('/v1/server/upgrade_plan', params, 'POST')
docs: /v1/server/upgrade_plan
          POST - account
          Upgrade the plan of a virtual machine. The virtual machine will be
          rebooted upon a successful upgrade.
  
          Link: https://www.vultr.com/api/#server_upgrade_plan