def get_url_usa_cases(states, daily):
    """    
    Build full url to send request to the covid tracking api.

    Args:
        states (string): states code to build full url.
        daily (string): show current data or daily data from first cases

    Returns:
        string: a full url to send api requests
    """
    link = 'https://covidtracking.com/api/v1/states/'
    if daily:
        extension = '/daily.json'
    else:
        extension = '/current.json'
    if states != 'all':
        url = link + states + extension
        return url
    else:
        url = link + extension
        return url