Python for Lisp Programmers (2000)(norvig.com)

    (def-tree T1
        root (A B C)
        A (D E)
        B (E F)
        ...)

  with open('foo.txt', 'w') as f:
      print('hello, world', file=f)

  with open('foo.txt') as f:
      print(f.readline())

  (with-open-file (f "foo.txt" :direction :output :if-exists :supersede)
    (format f "hello, world~%"))

  (with-open-file (f "foo.txt")
    (format t "~a~%" (read-line f)))

    CL-USER> (documentation '*print-readably* 'variable)
    "If true, all objects will be printed readably. If readable printing
      is impossible, an error will be signalled. This overrides the value of
      *PRINT-ESCAPE*."
    CL-USER> (documentation '+ 'variable)
    "the value of the most recent top level READ"
    CL-USER> (defvar *variable* nil "a variable")
    *VARIABLE*
    CL-USER> (documentation '*variable* 'variable)
    "a variable"

    (generate 'sentence)