Textbook chapters on optional parameters, tuples, sorted
Add reading response questions wk6
Merge pull request #34 from aerenchyma/add_wk6_resp

Add reading response questions wk6
added link to PS5
merged in pip
moved Tom Leher note because it seemed to be in mid-thought place -- moved below active code for base numbers
changed name of active code to make output got to correct box
swapped order of code in active code ch09_tuple4 such that error happens on last line
switched around language in paragraph following ch09_tuple4
fixed grammar in test_questiontuples_3
added more print statements to make cp_09_tuple5 and 6 more readable
removed comment in exercise 1 because i think it makes problem more clear
removed def absolute(x): from sort_8 because it make the system easier to work with.