wrap a chain of callables

chain.py

def chain(iterable):
    i, f = 0, None
    scope = {}
    loc = []
    for i, f in enumerate(iterable):
        name = '_' + str(i)
        scope[name] = f
        loc.append(name + '(*a,**k)')
    if i == 0:
        return f
    else:
        exec('def _(*a,**k):' + ';'.join(loc), scope)
        return scope['_']