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The computational task for this assignment is to design an algorithm and write a python program script according to your algorithm with appropriate functions which will . The script should take a date in the "YYYYMMDD" format and the number of day days before or after the given date as the command line arguments, calculate and output to the standard output data channel the actual targeted date which is the number of day before or after the given date in the same format.

== Coding Standard ==Your python script must follow the following coding guide:

* Name your python script as a1_[student_id].py, where [student_id] is your Seneca email user name.* Your python script must support two command line arguments: (1) any valid date in YYYYMMDD format, (2) number of days before or after the given date.* If there are less or more than two command line arguments given on the command line, your script should display the correct usage message and exit. = Computation Requirements === Algorithm Design ==* Write a step-by-step instructions in English on how to figure out a date which is n days before or after a given date.* While you are working on the step-by-step instructions, note that there are different number of days in each month and some years have 365 days and some years have 366 days.* You should also do some research to find out when we started using the Calendar in the current form. (This will pose a limit on the validity of your algorithm.) == Required Modules and Functions ==You must have <b><font color='blue'>Your python script is allowed to import only the <u>os and sys</u> modules from the standard library and all the built-in modules.</font></b> Based on your algorithm designed for this assignment, you should at least have the following three functions defined in your python programscript (see later section on the purpose of each function):* dbda()* tomorrow()* yesterday()You can also create additional functions to improved the re-usability of your python code by adding the following functions:

* yesterdayusage()

* Please use python's docstring to document your python script and each of the functions you created for this assignment. The docstring should describle 'what' the function does, not 'how' it does.* Please add The following shows the docstring that was added to the tomorrow() function to provide which provides the following information when call called with help(tomorrow) in the python interactive shell:

= Due Date = This Assignment is due on Sunday October 14, 2018. Submit on blackboard under the assignments section. Authorship Declaration ==All your Python code for this program assignment must be placed in a <font color='red'><b><u>single source python file</u></b></font>. Please include the following declaration by <b><u>youas the docstring</u></b> as a comment in your Python source code file (replace "Student Name" with your own name):

except those provided by the course instructor, including any person, textbook, or on-line resource. I have not shared this python program script with anyone or anything except for submission for grading. I understand that the Academic Honesty Policy will be enforced and violators will be reported and appropriate action will be taken.

= Instruction === Program Name Tests and valid command line arguments Test results ==Name You must name your python3 program python 3 script as <code>a1_[Student_id].py</code>. The following examples assumes that the student_id is rchan.The program script should accept two command line parametersarguments, the first one is the date in "YYYYMMDD" format, and the second one is the number of day from the given date, a positive value indicates the number of days after the given date, and a negative value indicates the number of days before the given date. There is an option called --step that makes the program print out all dates until the final target date. If the "YYYYMMDD" format is broken give an appropriate error message. Invalid months (>12) or invalid days of month(different for each month), should be detected and give appropriate error messages. For examples:* <b><code>python3 rchana1_rchan.py 20180101 1</code></b>, and the output should be<br />

* <b><code>python3 rchana1_rchan.py 20180101 -1</code></b>, and the output should be<br />

* <b><code>python3 rchana1_rchan.py 20180101 2</code></b>, and the output should be<br />

* <b><code>python3 rchana1_rchan.py --step 20180101 3</code></b>, and the output should be<br />

* <b><code>python3 rchana1_rchan.py 20180701 500</code></b>, and the output should be<br />

* <b><code>python3 rchana1_rchan.py 20189901 2</code></b>, and the output should be<br />

* <b><code>python3 rchana1_rchan.py 20180199 2</code></b>, and the output should be<br />

* <b><code>python3 rchana1_rchan.py 2018 2</code></b>, and the output should be<br />

If there is too few or too many command line parameters arguments given, display the proper usage.

== Program Script structure and sample template ==Your program code should all be in a single python file with at least the functions mentioned above: leapyeardbda(), tomorrow(), mainand yesterday(). You can also add additional functions based on your algorithm, tomorrowe.g.: leapyear(), validdate(), yesterdayusage():, etc

* The yesterdayusage() function will take a date in "YYYYMMDD" format no argument and return the date of the previous day in the same format. * The tomorrow() function will take a date in "YYYYMMDD" format and return string describing the date usage of the next day in the same format. Next paragraph is a sample python code for the tomorrow() functionscript. 

def dbda(yyyymmdd,days): ... setup loop call tomorrow or yesterday as appropriate return target_day  if __name__ == "__main__":

.. set loop based on the number of days given .. call tomorrowdbda() or yesterday() as appropriate