Pyton diner/dinner - with hash

nawords = getwords("enable-wordlist.txt")

# Create a hash, aka dictionary, for fast lookup of words
nahash = {w:True for w in nawords}

# Generate set of possible "words" by doubling every character
def dcands(w):
    return set([w[:i] + w[i] + w[i:] for i in range(len(w))])

# Generate list of all valid (baseword, transformed word) pairs
def dopfast(ws, wordhash):
    return [(w,c) for w in ws for c in dcands(w) if wordhash.get(c, False)]

dopfast(nawords, nahash)