def display_for_human(repo_list, list_content, display_callback):
    """Display installed collections in a format readable but probably not prefered by some humans"""
    INDENT = ' '
    for repo_item in repo_list:
        repo_msg = '{installed_repository.repository_spec.ns_n_v}'
        display_callback(repo_msg.format(**repo_item))
        if not list_content:
            continue
        for content_item_type_key, content_items_data in repo_item[
            'content_items'].items():
            content_type_msg = '{indent:2}- {content_item_type}'.format(
                content_item_type=content_item_type_key, indent=INDENT)
            display_callback(content_type_msg)
            content_msg = '{indent:4}- {name}'
            for content_item_data in content_items_data:
                display_callback(content_msg.format(indent=INDENT, name=
                    content_item_data['name']))
