[Grace-core] Assignment return values and null

[Andrew P. Black]

On 26 Jun 2012, at 12:59 , Michael Homer wrote:

> It should obviously be an iterator, but only character iteration is implemented at the moment. Returning a variant type would be sensible for the manual case. 

I feel that having library methods with block arguments is much more readable and doesn't require the use of types, or of case to later distinguish the types.

	Andrew