'For a regular verb (base form), returns the forms using a rule-based approach.'

def find_lexeme(self, verb):

    v = verb.lower()
    b = b0 = re.sub('en$', '', re.sub('ln$', 'l', re.sub('rn$', 'r', v)))
    (x, x1, x2) = ('', '', '')
    for prefix in prefix_separable:
        if v.startswith(prefix):
            (b, x) = (b[len(prefix):], prefix)
            x1 = ('    ' + x).rstrip()
            x2 = (x + 'ge')
            break
    pl = ((b.endswith('el') and (b[:(-2)] + 'l')) or b)
    pw = ((v.endswith(('ln', 'rn')) and v) or (b + 'en'))
    pr = ((b.endswith(('d', 't')) and (b + 'e')) or b)
    p2 = ((pr.endswith(('s', 'z')) and (pr + 't')) or (pr + 'st'))
    pp = ((v.endswith(('en', 'ln', 'rn')) and (v + 'd')) or (v + 'end'))
    pt = (encode_sz(pr) + 't')
    ge = (((v.startswith(prefix_inseparable) or b.endswith(('r', 't'))) and pt) or ('ge' + pt))
    ge = ((x and ((x + 'ge') + pt)) or ge)
    s1 = encode_sz(pl)
    s2 = encode_sz(pt)
    lexeme = a = [v, ((pl + 'e') + x1), (p2 + x1), ((pr + 't') + x1), (pw + x1), ((pr + 't') + x1), pp, ((pt + 'e') + x1), ((pt + 'est') + x1), ((pt + 'e') + x1), ((pt + 'en') + x1), ((pt + 'et') + x1), ge, ((b + 'e') + x1), ((pr + 't') + x1), (x + pw), ((s1 + 'e') + x1), ((s1 + 'est') + x1), ((s1 + 'en') + x1), ((s1 + 'et') + x1), ((s2 + 'e') + x1), ((s2 + 'est') + x1), ((s2 + 'en') + x1), ((s2 + 'et') + x1)]
    if (encode_sz(v) in self):
        a = self[encode_sz(v)]
        a = ((([decode_sz(v) for v in a[:7]] + a[7:13]) + [decode_sz(v) for v in a[13:20]]) + a[20:])
    return [(a[i] or lexeme[i]) for i in range(len(a))]
