(begin ) returns the last expression in a sequence after evaluating the sequence in order. (begin_random ) evaluates the sequence of expressions in random order and returns the last value evaluated. (if []) returns one of two values based on the value of a condition. (cond ( ) [( ) [...]]) returns the value associated with the first true condition. (set ) set the value of a global variable. (and ) returns true if all specified expressions are true. (or ) returns true if any specified expressions are true. (+ ) returns the sum of all specified expressions. (- ) returns the difference of two expressions. (* ) returns the product of all specified expressions. (/ ) returns the quotient of two expressions. (min ) returns the minimum of all specified expressions. (max ) returns the maximum of all specified expressions. (= ) returns true if two expressions are equal (!= ) returns true if two expressions are not equal (> ) returns true if the first number is larger than the second. (< ) returns true if the first number is smaller than the second. (>= ) returns true if the first number is larger than or equal to the second. (<= ) returns true if the first number is smaller than or equal to the second. (sleep [