How do I prune a hebe?

I have a lovely pink hebe in my garden. It is flowering its heart out at the moment. When should I prune it? And how far back can I go? It is so pretty that I don't want to spoil it.
Thank you in advance!!

Answers:
I want to thank you for this question. I had never heard of a Hebe before, but learned something today. The first group of stuff is a website that sells different kinds of Hebe and has a nice website with pictures. The second is something I copied and pasted from the source listed below. Hope this helps.

bramblebank@intergate.com
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