Answer 1

the second value is returned only if the first value is not among the keys. it is sort of a replacement for the searched value if it is not present. if you have dictionary
dict={1:2,3:4}
dict.get(3,'not there') would return 4,since that is the value associated with key 3, but dict.get(5,'not there') would return 'not there', since there is no value associated with 5