*** Python applying learnings from 1..6
**** Lecture notes
     - Previous topics covered:
       - Printing
       - Formatting
       - Variables
       - Escape Sequences
       - Inputting text
       - Reading arguments / using argv
       - Reading files
       - Defining methods
       - Boolean logic
       - Branching using if/else/elif
       - Loops: for/while
     - Today we write a calculator that saves results in a file in python
       - How it works in general
         You read the input until you read a line that only contains a
         "q". Every input line consists of numbers separated by a
         space. For instance "4 5 9". You will need to .split() the
         input.
     - Steps
       - Create a python script named "calc.py"
       - It takes 1 command line argument (argv), which is the filename
         - We will store the calculations *and* results in this file
       - Create a method named "input_and_calculate_one_line"
         - It does not have any arguments
         - It reads one line via *input*
         - It splits the input (let's say "4 5 9" => [ "4", "5", "9") ])
         - It calculates the result (f.i. 4+5+9 = 18) and stores it in
           a variable (use *sum* over the *list*)
         - It returns a string of the format "4 + 5 + 9 = 18"
         - If the line only contains a "q" it return "" (an empty string)
       - Create a method named "editor" that takes a filename as an argument
         - It opens the file for writing
         - It uses input_and_calculate_one_line in a while loop
         - while the return result is not "", we append the string to
           the file
         - When the return result is "", the function exits

*** State:
input_and_calculate_one_line is complete, however it's probably a garbage implementation.
Spent too much time on converting back and forth and getting the output right. 

Editor (file io) is not complete yet 
