docstr: Ignore callback reconnect
docstr_tok: ["Ignore","callback","reconnect"]
code: def test_reconnect(self):
      """Ignore callback reconnect"""
      em = EventEmitter(type="test_event")
  
      def cb(ev):
          self.result += 1
  
      em.connect(cb)
      em.connect(cb)  # second connection should do nothing.
      self.result = 0
      em()
      assert self.result == 1
  
imports: import unittest
  import copy
  import functools
  from vispy.util.event import Event, EventEmitter
  from vispy.testing import run_tests_if_main, assert_raises, assert_equal
label_desc: Use image node_id 10 for calling the TestEmitters obj's underlying member method code with example usage: obj.test_reconnect() without return types