SCHEME PROBLEM:

1. Define a recursive Scheme procedure (remove-last-even lst) which returns the list with the last even number removed. For example: (remove-last-even '(1 -2 -3 4 5)) (1 -2 -3 5)

2. Write a Scheme procedure (manhattan a b) which, given two pairs representing points on the Cartesian coordinate system, returns the Manhattan distance between the two points.

3. Write a Scheme procedure remove-dups which takes a list of words/letters as input and returns the list with consecutive repeated words/letters removed. Note that multiple instances of a letter are allowed if they are not consecutive. For example, (remove-dups (a b c c d d c a a b)) (a b c d c a b)