 A simple way to read the meaning of a computation is to consider it as a mechanical procedure consisting of a finite number of steps that, when completed, yields a result.This interpretation is inadequate, however, for procedures that do not terminate after a finite number of steps, but nonetheless have an intuitive meaning.Consider, for example, a procedure for computing the decimal expansion of ; if implemented appropriately, it can provide partial output as it "runs", and this ongoing output is a natural way to assign meaning to the computation.