Take the 2-minute tour ×  Possible Duplicate: Flatten a list
using only the forms in “The Little Schemer”  I simply want to
turn '(a b (c d) e) into '(a b c d e) (i.e., insert each member
of the inner list into the outer list, while maintaining the
order of the elements).  There has to be a simple way to do
this, but it eludes me for some reason.  share|improve this
question  marked as duplicate by Barmar, iMat, jonsca, Vikdor,
Jason Sturges Sep 28 '12 at 3:16   Spoiler:
stackoverflow.com/a/7324493/13. (If this is for homework, please
don't read that thread until you've tried solving it first!) – 
Chris Jester-Young Sep 28 '12 at 0:50  1 Answer 1  You see that
'(a b (c d) e) is a tree, don't you? Something like   In this
representation, nodes are lists, and leafs are symbols. What you
could do, it print all the leafs of the tree:    1. if the tree
is empty (= is the empty list), then stop   2. If the tree is
not empty, then     1. If the tree's CAR is a symbol, print it,
then process the CDR of the tree     2