Previous / current / next iterator in Python 3

pcniter.py

def previous_current_next(iterable):
    """Make an iterator that yields an (previous, current, next) tuple per element.
 
    Returns None if the value does not make sense (i.e. previous before
    first and next after last).
    """
    iterable=iter(iterable)
    prv = None
    try:
        cur = next(iterable)
    except StopIteration:
        return
    try:
        while True:
            nxt = next(iterable)
            yield (prv,cur,nxt)
            prv = cur
            cur = nxt
    except StopIteration:
        yield (prv,cur,None)
 
# Examples
print(list(previous_current_next([])))
print(list(previous_current_next([1])))
print(list(previous_current_next([1,2])))
print(list(previous_current_next([1,2,3])))