def get_video_id_by_number(number, results):
    """Get video id by its number from the list of search results generated by search_by_keyword
function call.

Videos are numbered from 1 to maxResults (optional search parameter,
set by default to 5, see https://developers.google.com/youtube/v3/docs/search/list)
as in results list.

Args:
    number (int): number of video whose id is requested
    results (list): list of search results generated by search_by_keyword function call

Returns:
    string: youtube video id
    """

    return results[number-1]['id']['videoId']