text: 
  # Introduction to python:
  # in python comment lines by '#'
  
  # 1. Working environment: 2 screens, good keyboard and mouse (screen attach to mobile computer).
  
  # 2. Install Python programming language
  # downlaod from python.org/downloads/
  # run file (select add to path option)
  # run the idle program
  
  # for installation instructions for Mac and Windows see:
  # https://www.youtube.com/watch?v=YYXdXT2l-Gg
  
  ## 3. Guides for python in Hebrew:
  ## https://www.youtube.com/watch?v=fNX8tKnozF0&list=PLEtZq1oDporhAPIlKhfRCpcxjpXjSeR2z
  ## https://www.youtube.com/watch?v=jwmU-L8ihwg
  ## https://www.youtube.com/watch?v=hNuJ7Doc7Sg
  ##
  # English guide (in depth)
  # https://www.youtube.com/watch?v=OFrLs22MDAw&list=PLzMcBGfZo4-mFu00qxl0a67RhjjZj3jXm&index=1
  
  
  ## 4. keyboard shortcuts for IDLE in moodle.
  
  # 5. Print
  print("Hello World!")
  # get user input using input()
  # print("Please enter first name: ")
  # name = input()
  # print hello with the user name
  # print('Hello ,', name)
  # # what will be the following output?
  # a = "a1"
  # b = "b1"
  # print(a+b)
  
  # 6. data types:
  # int 0 1 2 -5
  # str "ewfr" "3"
  # float 3.14 2.71
  # we can get the type of a variable by type command
  # a = 2
  # str1 = "2"
  # f1 = 2.71
  # print("a is of type ,", type(a))
  ## print("str1 is of type ,", type(str1))
  # print("f1 is of type ,", type(f1))
  
  # 7. Variables naming conventions \ rules:
  # cannot start with a number (can end with a number)
  # name1 - legal
  # 1name , na me - not legal
  # case sensative - name, NAME , Name, nAme are all different variables.
  
  
  
  
  # 8 arrithmetic:
  # num1 = 1.5
  # num2 = 5
  # print(num1+num2)
  # print(num1-num2)
  # print(num1*num2)
  # print(num1/num2)
  # print(num2 ** 2) # power
  # print(num2 ** 3)
  # print(num2//num1) # int part of devision
  # print(num2 % num1) # module
  
  ### 9 casting
  ##num1 = input('enter num1\n') # end of line by \n
  ##num2 = input('enter num2\n')
  ##print(num1+num2) # Is this the expected result?
  ### Type of input is always str, + operator results in concatination
  ### Casting will solve this:
  ##print(float(num1)+float(num2))
  ### or save to variable
  ##res = float(num1)+float(num2)
  ##print(res)
  
  # 10. Conditions: > < == != (bigger, smaller, is equal, is not equal
  # print(18>2)
  # print(18<2)
  # print(18==2) # do not confuse with '='. this is '=='
  # print(18!=2)
  
  
  # # if else
  # num = input()
  # if num > 0:
  #     print("positive")
  # else:
  #     print("not positive")  # why not negative?
  
  # Homework (self assignment)
  # 1. Install python
  # 2. Run first program that print "Hello World!" on screen.
  