import datetime from dateutil import parser

def str_to_time(timestamp): """ Returns the datetime object for the given timestamp (or None if the stamp is invalid) This function should just use the parse function in dateutil.parser to convert the timestamp to a datetime object. If it is not a valid date (so the parser crashes), this function should return None. Parameter timestamp: The time stamp to convert Precondition: timestamp is a string """ # Hint: Use a try-except to return None if parsing fails try: timestamp = parser.parse(timestamp) return timestamp except: return None

def sunset(date,daycycle): """ Returns the sunset datetime (day and time) for the given date This function looks up the sunset from the given daycycle dictionary. If the daycycle dictionary is missing the necessary information, this function returns the value None. A daycycle dictionary has keys for several years (as int). The value for each year is also a dictionary, taking strings of the form 'mm-dd'. The value for that key is a THIRD dictionary, with two keys "sunrise" and "sunset". The value for each of those two keys is a string in 24-hour time format. For example, here is what part of a daycycle dictionary might look like: "2015": { "01-01": { "sunrise": "07:35", "sunset": "16:44" }, "01-02": { "sunrise": "07:36", "sunset": "16:45" }, ... } Parameter date: The date to check Precondition: date is a date object Parameter daycycle: The daycycle dictionary Precondition: daycycle is a valid daycycle dictionary, as described above """ # HINT: ISO FORMAT IS 'yyyy-mm-ddThh:mm'. For the sunrise value, construct a # string in ISO format and call str_to_time.