Worksheet #1, Period 1 September 2000

1. Write a function called cons-all which will take any number if arguments as
   long as the first one is a list. It will put the other arguments into the list.
      Example: (cons-all '(x y) 'a 'b 'c) returns (a b c x y)
         (cons-all '(x y) '(a)) returns ((a) x y)
   
   
2. Write a function called which which will determine the type of argument it receives.
   >   Example (which 'a) returns atom
         (which 7) returns number
         (which '(a b)) returns list
         (which nil) returns empty list
   
   
3. Write a function intersect which will accept two lists as parameters and will
   return the intersection of the two lists.
   >   Example (intersect '(a b c d) '(b d)) returns (b d)
         (intersect '(a b c d) '(w x y)) returns nil
         (intersect '(a b c) '(a b c)) returns (a b c)
   
   
4. Write a function pair-it which will receive 2 parameters, an atom and a list of lists.
   If the atom appears in any of the sublists, return the first appearance of that sublist.
      Example: (pair-it 'a '((m n) (a b) (r s))) returns (a b)
         (pair-it 'x '((a b) (w x) (x y))) returns (w x)
         (pair-it 'q '((a)(b)(c))) returns nil