def METHOD_NAME(self, custom_values=None):
    """Returns a simple submission instance."""
    custom_values = {} if custom_values is None else custom_values
    simple_xforms = XForm.objects.filter(title="WaterSimple")
    if simple_xforms.count() == 0:
        xform = self.create_simple_xform()
    else:
        xform = simple_xforms[0]
    # these values can be overridden with custom values
    values = {
        "device_id": "12345",
        "start": "2011-01-01T09:50:06.966",
        "end": "2011-01-01T09:53:22.965",
        "geopoint": "40.783594633609184 -73.96436698913574 300.0 4.0",
    }
    if "start" in custom_values:
        start = custom_values["start"]
        custom_values["start"] = start.strftime(XFORM_TIME_FORMAT)
        # if no end_time is specified, defaults to 1 hour
        values["end"] = (start + ONE_HOUR).strftime(XFORM_TIME_FORMAT)
    if "end" in custom_values:
        custom_values["end"] = custom_values["end"].strftime(XFORM_TIME_FORMAT)
    values.update(custom_values)
    water_simple_survey = _load_simple_survey_object()
    simple_survey = water_simple_survey.instantiate()
    for k, v in values.items():
        simple_survey.answer(name=k, value=v)
    # setting the id_string so that it doesn't end up
    # with the timestamp of the new survey object
    # pylint: disable=protected-access
    simple_survey._id = xform.id_string
    instance_xml = simple_survey.to_xml()
    return Instance(xml=instance_xml)