Camp David in 1935 and was completed in 1938. In 1942, President Franklin D. Roosevelt converted it to a presidential retreat and renamed it "Shangri-La" (for the fictional Himalayan paradise in the 1933 novel "Lost Horizon" by British author James Hilton, which he had jokingly referenced as the source of the Doolittle Raid earlier that year). Camp David received its present name from Dwight D. Eisenhower, in honor of his father and grandson, both named David. The Catoctin Mountain Park does not indicate the location of Camp David on park maps due to privacy and security concerns, although it can be seen
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