function for returning the selectable shells of a poly

shells.py

def getShellFaces(poly, asString=False):
    shells = set()
    faces = set()
    total = cmds.polyEvaluate(poly, s=True)
    
    for f in xrange(cmds.polyEvaluate(poly, f=True)):

        if len(shells) >= total:
            break
        if f in faces:
            continue

        shell = cmds.polySelect(poly, extendToShell=f)
        faces.update(shell)
        
        if asString:
            val = "%s.f[%d:%d]" % (poly, min(shell), max(shell))
        else:
            val = min(shell)
        
        shells.add(val)

    return list(shells) 

poly = 'polySurface1'

# get the first face of each shell to be selected 
# later with polySelect
faceIds = getShellFaces(poly)
for f in shells:
    cmds.polySelect(poly, extendToShell=f)

# get the string name of the entire shell in the
# form of polySurface1.f[x:y] to be used with select
shells = getShellFaces(poly, True)
for f in shells:
    cmds.select(f)

hello!
what if faces are not numbered in ascending order? what if faces 0, 3, 5, and 7 compose into shell?

Just what I needed. Thanks Justin.
@sickiziu, as each face is extended to a group and then added to a set, this should work for all scenarios.

Thanks! should be like this I assume.

faceIds = getShellFaces(poly)
for f in faceIds: