Lost world Arthur Gordon Pym of Nantucket" (1838) has certain lost world elements towards the end of the tale. James Hilton's "Lost Horizon" (1933) enjoyed popular success in using the genre as a takeoff for popular philosophy and social comment. It introduced the name Shangri-La, a meme for the idealization of the lost world as a paradise. Similar books where the inhabitants of the lost world are seen as superior to the outsiders, are Joseph O'Neill's "Land under England" (1935) and Douglas Valder Duff's "Jack Harding’s Quest" (1939). Hergé also explores the theme in his comics "The Seven Crystal Balls" and "Prisoners
S-expression be formatted as pretty printed S-expressions using the function PPRINT (note: with two Ps, short for "pretty"-print). Lisp programs are valid s-expressions, but not all s-expressions are valid Lisp programs. codice_21 is a valid s-expression, but not a valid Lisp program, since Lisp uses prefix notation and a floating point number (here 1.0) is not valid as an operation (the first element of the expression). An S-expression preceded by a single quotation mark, as in codice_22, is syntactic sugar for a quoted S-expression, in this case codice_23. S-Expressions are often compared to XML, a key difference being that S-Expressions are