 { $description
     "Returns all the ways to take n (possibly the same) items from the "
     "sequence of items."
-} 
+}
 { $examples
     { $example
         "USING: math.combinatorics prettyprint ;"


HELP: each-permutation
{ $values { "seq" sequence } { "quot" { $quotation "( seq -- )" } } }
{ $description "Applies the quotation to each permuation of " { $snippet "seq" } " in order." } ;

HELP: inverse-permutation
{ $values { "seq" sequence } { "permutation" sequence } }

HELP: factorial
{ $values { "n" "a non-negative integer" } { "n!" integer } }
{ $description "Outputs the product of all positive integers less than or equal to " { $snippet "n" } "." }
{ $examples
    { $example "USING: math.combinatorics prettyprint ;"
        "4 factorial ." "24" }
} ;
