Why are functions atomic?

[John Nagle]

Martin v. Löwis wrote:
> Michael schrieb:
> 
>>A bit more info, but still no clear picture about why functions are
>>mutable but have immutable copy symantics.  There are arguments why
>>functions should be immutable, but the decision was to make user-
>>defined functions mutable.  My question is still: why the present
>>ummutable copy symantics?
> 
> 
> The answer is really really simple. The implementation of copy predates
> mutability. When the copy code was written, functions *were* immutable.
> When functions became mutable, the copy code was not changed, and
> nobody noticed or complained.

     That's probably an indication that mutable functions don't
get used all that much.  Are there any instances of them in the
standard Python libraries?

				John Nagle