Why does the following not succeed in producing a sequence of length 4 ?
$$
\mathrm{i} \leftarrow \text { (Primes new) select: }[: \mathrm{x} \mid \mathrm{x}<10]
$$
Show how to implement methods for the following messages:
while: The argument must be a one-parameter block returning a boolean value. Return values from the underlying generator as long as the block evaluates to true. Terminate when the underlying generator is exhausted or when a value is found for which the block is not true.
until: Like while: The argument must be one-parameter block returning a boolean value. Produce values from the underlying generator until the block returns true, or until the generator is exhausted.
Is it necessary to implement both of these in terms of AbstractGenerator? Show how, if a method exists for either one, the other can be implemented in terms of it.