1. Write a Python function named Random-studentID() that randomly generate any 100 possible student IDs which have 9 digits and start with 900 number, and output these student ID into a text file named randomID.txt.

2. Unix time/ Epoch time is the number of seconds since midnight of January 1st 1970. Write a Python function named convert_utime() that reads the timestamps from a file named unixttimestamp.txt (see attached) and displays the human readable form of the supplied Unix timestamp.

3. Write a Python function named register_user() that checks if a user is registered for a conference. The function must add the user if she/he is not in the list. The set data structure should be used to avoid duplicate usernames. The user input must be checked against registered users stored in a text file named conference.txt