"The Common Lisp `loop' macro.
Valid clauses include:
For clauses:
- for VAR from/upfrom/downfrom EXPR1 to/upto/downto/above/below EXPR2 by EXPR3
+ for VAR from/upfrom/downfrom EXPR1 to/upto/downto/above/below EXPR2 [by EXPR3]
for VAR = EXPR1 then EXPR2
- for VAR in/on/in-ref LIST by FUNC
+ for VAR in/on/in-ref LIST [by FUNC]
for VAR across/across-ref ARRAY
for VAR being:
the elements of/of-ref SEQUENCE [using (index VAR2)]