generator object or 'send' method?

[John O'Hagan]

On Mon, 9 Feb 2009, Aaron Brady wrote:
> Hello,
>
> I am writing a generator to return a sequence of numbers with some
> variation.  The parameters of the variation can be changed by the
> caller, even after the generator is started. 
[...]

I would love to see a simple code example of this if you have one; I've been 
wanting to do this but couldn't even get started.

Regards,

John