def create_field_override_choices(override_map=None):
    """
    This is a utility function that takes the output from the map_override_fields method,
    and converts it to a tuple suitable for a "choices" option to a field.
    
    The map is a list of dicts.
    We want to return a list of tuples (value_to_store, value_to_show)
    """
    if override_map:
        choices = []
        for item in override_map:
            choices.append(item['field'], '{} ({})'.format(item['field'],
                item['field_type']))
        return choices
    return None
