invokes TouchWorksMagicConstants.ACTION_GET_TASK_LIST action
        :param since - If given a datetime, retrieves only tasks created (or last modified)
            after that date and time. Defaults to 1/1/1900.
        :param task_status - Optional list of pipe-delimited task status names.
            For example, "Active|In Progress|Complete".
        :param task_types - Optional list of pipe-delimited task type names.
            For example, "Sign Note|Verify Result|MedRenewal"
        :return: JSON response

def get_task_list(self, since='', task_types='', task_status=''):
        """
        invokes TouchWorksMagicConstants.ACTION_GET_TASK_LIST action
        :param since - If given a datetime, retrieves only tasks created (or last modified)
            after that date and time. Defaults to 1/1/1900.
        :param task_status - Optional list of pipe-delimited task status names.
            For example, "Active|In Progress|Complete".
        :param task_types - Optional list of pipe-delimited task type names.
            For example, "Sign Note|Verify Result|MedRenewal"
        :return: JSON response
        """
        magic = self._magic_json(
            action=TouchWorksMagicConstants.ACTION_GET_TASK_LIST,
            parameter1=since,
            parameter2=task_types,
            parameter3=task_status)
        response = self._http_request(TouchWorksEndPoints.MAGIC_JSON, data=magic)
        result = self._get_results_or_raise_if_magic_invalid(
            magic,
            response,
            TouchWorksMagicConstants.RESULT_GET_ENCOUNTER_LIST_FOR_PATIENT)
        return result