# Test case.  This tests the "part of the circuit isolated from
#  voltage" case.  It's not quite as simply as possible (that would be
#  a circuit with no voltage nodes at all) but it's pretty simple:
#
#	0V--a----/\/\/\/----b--1V
#
#	    c----/\/\/\/----d

V a 0
V b 1
R a b 1
R c d 1