def float_seconds_from_string(str_hh_mm_ss_ms):
    """Convert to seconds in float, from string in format hh:mm:ss

    Args:
        string_timedelta (str): format hh:mm:ss.ms

    Returns:
        Float: timedelta in seconds
    """

    hr, min, sec = map(float, str_hh_mm_ss_ms.split(':'))
    float_sec_timedelta = sec + min*60 + hr*60*60

    return float_sec_timedelta