def manage_time(timestamp):
    """
    Given the string representation of a the time using the
    "minutes:seconds[:miliseconds]" representation, returns the number
    of seconds using double precision
    """

    time_strip = timestamp.split(":")
    seconds = int(time_strip[0]) * 60 + int(time_strip[1])

    # Add miliseconds
    if len(time_strip) == 3:
        seconds += int(time_strip[2]) / 60

    return seconds