added link for Scala's assert
flatMap that sh..
9.9 added tests for json parser
Exercise 2.2
Exercises 2.1, 2.3, 2.4 and 2.5
Exercise 3.2
Exercise 3.3
Exercise 3.4
Exercise 3.5
Exercise 3.6
Exercise 3.9
Exercise 3.10
Exercise 3.11
Exercise 3.12
Exercise 3.14
Exercise 3.15
Exercise 3.16
Exercise 3.17
Exercise 3.18
Exercise 3.19