Lie Ryan <lie.1296 at gmail.com> writes: > I guess in python, None as the missing datum idiom is still quite prevalent: Well, sometimes there is no way around it, but: > def cat_list(a=None, b=None): > # poor man's list concatenation > if a is None and b is None: return [] > if a is None: return b > if b is None: return a > return a + b def cat_list(a=[], b=[]): return a + b