a possibly foolish question about slices

[Andrew Koenig]

Suppose x is a string or list, and I want to refer to
a subsequence of x with length n starting at position p.
under the assumption that this subsequence is entirely

To do so, I can use x[p:p+n] in all circumstances but one,
namely when p < 0 and p == -n.  Is there a similarly concise
expression that works even in this special case?

-- 
Andrew Koenig, ark at research.att.com, http://www.research.att.com/info/ark