CSE 1310 Lab Homework II Assignment #2:

Program Purpose :  In Assignment #2 you will turn two of your previous programs into functions 
and then write a new program that calls those functions and others as chosen by the user from a menu.  

Problem Description:

You are going to write a program that allows the user to enter two Cartesian points, then allows 
them to find the distance between them, or the slope of the line that connects them, or determine 
what quadrant the first point is in, or determine what quadrant the second point is in.  The user 
should be allowed to continue to choose any one of these actions repeatedly and should have a 
choice to stop.  Your program should also give a message if no valid choice was made and then 
let the user make another choice.
Your assignment should be written as a program stored in a file with the name given as below 
(see Implementation Requirements).  You must write three functions to be called by your program. 

1) Distance function - using the code from your previous assignment (assuming it works), 
turn the distance calculation into a function that takes in four parameters x1, y1, x2, and 
y2 and returns the distance from x1,y1 to x2,y2.  You will have to modify your code somewhat 
since we are no longer measuring from the origin.  Note that the points for this assignment 
can be in any quadrant.  The function should calculate and return the distance but not print it.

2) Slope function - using the code from the Assignment #1 part of HW II, write a slope 
function that takes in four parameters x1, y1,x2, and y2 and returns the slope of the line 
(giving rise and run) that connects them.  The slope function should also return the y-intercept 
value for the line.  Note that this means there are multiple return values from the function.  
The function should calculate and return the three values but not print them.

3) Quadrant function - write a function to determine which quadrant of a Cartesian plane a 
point will fall in.  Take in a point (x, y) and return the number representing the quadrant in 
the Cartesian plane.

The functions should be in the program file prior to the main body of the code.  The main body 
of the code should give the user a brief overview of what the program does, then ask the user 
for the input values.  Be sure to error check the user input to make sure they are valid types 
of data for Cartesian coordinates.  Once the data is validated, then give the user a menu to 
choose from.  Based on the user choice the program should call the appropriate function with 
the correct inputs and then give output to the user based on the results of the function.  The 
program should let the user continue to choose actions from the menu until the user chooses to 
end the program.  The program should print a concluding message for the user when the program ends.

Implementation Requirements

1) Required file name: points_plane.py 
2) Reuse code from Lab HW I and from Lab HW II Assignment 1
3) Write a Python program which calls at least three functions
4) Have a header comment in the file followed by the function definitions
5) The beginning of the main program code should be marked with a comment ### main ###
6) The functions should each have a short comment describing their purpose on the first line 
       following the function header, i.e. after the def line
7) The main program should have comments to describe the parts of the program