PyGtk3 Populate ComboBox from Glade in Python

test.glade

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <!-- interface-requires gtk+ 3.0 -->
  <object class="GtkListStore" id="myliststore">
    <columns>
      <!-- column-name code -->
      <column type="gchararray"/>
      <!-- column-name legible -->
      <column type="gchararray"/>
    </columns>
  </object>
  <object class="GtkWindow" id="window">
    <property name="can_focus">False</property>
    <property name="window_position">center-always</property>
    <property name="default_width">400</property>
    <signal name="destroy" handler="main_quit" swapped="no"/>
    <child>
      <object class="GtkBox" id="box">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <child>
          <object class="GtkLabel" id="label">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Best color in the world:</property>
          </object>
          <packing>
            <property name="expand">True</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkComboBox" id="mycombobox">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="model">myliststore</property>
            <signal name="changed" handler="combobox_changed" swapped="no"/>
            <child>
              <object class="GtkCellRendererText" id="renderer"/>
              <attributes>
                <attribute name="text">1</attribute>
              </attributes>
            </child>
          </object>
          <packing>
            <property name="expand">True</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

test.py

# A big thank you to Havoc
# http://stackoverflow.com/a/10527393/1695680

from gi.repository import Gtk
from os.path import abspath, dirname, join

WHERE_AM_I = abspath(dirname(__file__))

class MyApp(object):

    def __init__(self):
        # Build GUI
        self.builder = Gtk.Builder()
        self.glade_file = join(WHERE_AM_I, 'test.glade')
        self.builder.add_from_file(self.glade_file)

        # Get objects
        go = self.builder.get_object
        self.window = go('window')
        self.myliststore = go('myliststore')
        self.mycombobox = go('mycombobox')

        # Initialize interface
        colors = [
            ['#8C1700', 'Redish'],
            ['#008C24', 'Greenish'],
            ['#6B6BEE', 'Blueish'],

        ]
        for c in colors:
            self.myliststore.append(c)
        self.mycombobox.set_active(0)

        # Connect signals
        self.builder.connect_signals(self)

        # Everything is ready
        self.window.show()

    def main_quit(self, widget):
        Gtk.main_quit()

    def combobox_changed(self, widget, data=None):
        model = widget.get_model()
        active = widget.get_active()
        if active >= 0:
            code = model[active][0]
            print('The code of the selected color is {}'.format(code))
        else:
            print('No color selected')

if __name__ == '__main__':
    try:
        gui = MyApp()
        Gtk.main()
    except KeyboardInterrupt:
        pass