def select_parameter(*, url):
    """
    Select one parameter (start from the begin) from url from swagger.json
    For example:
    url in swagger = r"confirmation/{uidb64}/{token}/"
    parameter = uidb64
    pos_opened_curly_bracket = 13
    pos_closed_curly_bracket = 20
    """
    parameter = None
    pos_opened_curly_bracket = -1
    pos_closed_curly_bracket = -1

    pos_opened_curly_bracket = url.find('{')
    if pos_opened_curly_bracket >= 0:
        pos_closed_curly_bracket = url.find('}')
        if pos_closed_curly_bracket >= 0:
            parameter = url[pos_opened_curly_bracket+1:pos_closed_curly_bracket]
    return parameter, pos_opened_curly_bracket, pos_closed_curly_bracket