something to make it a little more efficient to
build stuff on long integers; some simple things which 
are much faster to do in C than in python:

e.g.   
   n.bitwid()    1+ floor(log2(abs(n)) - # of useful bits
    n.bit(x)       (n>>x)&1
    n.bit(hi,lo)    (n>>lo) & ( (1<<(hi-lo))-1)
      n.bitrev(m)  - reverse the lower m bits of n,
return that

      n.findup( val=1, startbit=0)
        "search leftwards for a bit matching 'val',
starting at
          bit 'startbit'; -1 if none"
      n.finddown(val=1, startbit=n.bitwid())
         " search rightwards"

And some which would depend on the underlying
implementation (which appears to be pretty much
cast in cement, if not actual stone) :


   n.bitarray()   returns array.array('H') containing
raw bits

   long_fromarray(seq, neg=0)  - reverse of n.bitarray

If there's any interest in this, and no reason to shoot it
down right away, I cld write a PEP on it.

It would also be nice to have field-insertion operators,
that raises the question of wether these should return
a new long, or wether they should be built on a 
mutable 'bit-sequence' type which can act like a long.
Maybe this should be an 'array-of-bit' suggestion....