'child_get_property(child, property_name, value=None)
:param child:
a widget which is a child of `self`
:type child: :obj:`Gtk.Widget`
:param property_name:
the name of the property to get
:type property_name: :obj:`str`
:param value:
Either :obj:`None` or a correctly initialized :obj:`GObject.Value`
:type value: :obj:`GObject.Value` or :obj:`None`
:returns: The Python value of the child property
{{ docs }}'

def child_get_property(self, child, property_name, value=None):

    if (value is None):
        prop = self.find_child_property(property_name)
        if (prop is None):
            raise ValueError(('Class    "%s"    does    not    contain    child    property    "%s"' % (self, property_name)))
        value = GObject.Value(prop.value_type)
    Gtk.Container.child_get_property(self, child, property_name, value)
    return value.get_value()
