which re a|l|t|e|r|n|a|t|i|v|e matched?

[Diez B. Roggisch]

> pat = reduce(lambda acc, key: "%s|(%s)" % (acc, key), d.keys())[1:]

Oops, forgot the first argument for acc, its "" of course:

pat = reduce(lambda acc, key: "%s|(%s)" % (acc, key), d.keys(), "")[1:]

Diez