slicing functionality for strings / Python suitability forbioinformatics

[jbperez808 at yahoo.com]

Having to do an array.array('c',...):

  >>> x=array.array('c','ATCTGACGTC')
  >>> x[1:9:2]=array.array('c','AAAA')
  >>> x.tostring()
  'AACAGACATC'

is a bit klunkier than one would want, but I guess
the efficient performance is the silver lining here.