# http://stupidpythonideas.blogspot.com/2014/01/grouping-into-runs-of-adjacent-values.html

def adjacent_key(cutoff=1, key=None, predicate=None):
    if key is None:
        key = lambda v: v
    if predicate is None:
        def predicate(lhs, rhs):
            return lhs - cutoff <= rhs <= lhs + cutoff
    class K(object):
        __slots__ = ['obj']
        def __init__(self, obj):
            self.obj = obj
        def __eq__(self, other):
            ret = predicate(key(self.obj), key(other.obj))
            if ret:
                self.obj = other.obj
            return ret
    return K

def first_and_last(iterable):
    start = end = next(iterable)
    for end in iterable: pass
    return start, end

def runs(iterable, *args, **kwargs):
    for k, g in itertools.groupby(iterable, adjacent_key(*args, **kwargs)):
        yield first_and_last(g)