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26.3 Conditional Evaluation of a Sequence of Expressions

and and or evaluate all their arguments, similar to begin, but evaluation stops as soon as one of the expressions evaluates to false or true, respectively.

— Syntax: and expr ...

Evaluate the exprs from left to right and stop evaluation as soon as one expression evaluates to #f; the remaining expressions are not evaluated. The value of the last evaluated expression is returned. If no expression evaluates to #f, the value of the last expression is returned.

If used without expressions, #t is returned.

— Syntax: or expr ...

Evaluate the exprs from left to right and stop evaluation as soon as one expression evaluates to a true value (that is, a value different from #f); the remaining expressions are not evaluated. The value of the last evaluated expression is returned. If all expressions evaluate to #f, #f is returned.

If used without expressions, #f is returned.