Coffee Example raises PatsyError

I was running through the coffee example and ran into an error. Here is the stack trace:
---------------------------------------------------------------------------
AssertionError                            Traceback (most recent call last)
<ipython-input-32-cc4172207ea4> in <module>()
     19 alpha = 0.05
     20 model = ' + '.join(coffee_design.columns)
---> 21 factorial_power = dexpy.power.f_power(model, coffee_design, sn, alpha)
     22 factorial_power.pop(0) # remove intercept
     23 

~/anaconda3/lib/python3.6/site-packages/dexpy/power.py in f_power(model, design, effect_size, alpha)
     30       [ 95.016, 49.003, 49.003, 49.003, 49.003 ]
     31     """
---> 32     X = dmatrix(model, design)
     33     residual_df = X.shape[0] - X.shape[1]
     34 

~/anaconda3/lib/python3.6/site-packages/patsy/highlevel.py in dmatrix(formula_like, data, eval_env, NA_action, return_type)
    289     eval_env = EvalEnvironment.capture(eval_env, reference=1)
    290     (lhs, rhs) = _do_highlevel_design(formula_like, data, eval_env,
--> 291                                       NA_action, return_type)
    292     if lhs.shape[1] != 0:
    293         raise PatsyError("encountered outcome variables for a model "

~/anaconda3/lib/python3.6/site-packages/patsy/highlevel.py in _do_highlevel_design(formula_like, data, eval_env, NA_action, return_type)
    163         return iter([data])
    164     design_infos = _try_incr_builders(formula_like, data_iter_maker, eval_env,
--> 165                                       NA_action)
    166     if design_infos is not None:
    167         return build_design_matrices(design_infos, data,

~/anaconda3/lib/python3.6/site-packages/patsy/highlevel.py in _try_incr_builders(formula_like, data_iter_maker, eval_env, NA_action)
     60                 "ascii-only, or else upgrade to Python 3.")
     61     if isinstance(formula_like, str):
---> 62         formula_like = ModelDesc.from_formula(formula_like)
     63         # fallthrough
     64     if isinstance(formula_like, ModelDesc):

~/anaconda3/lib/python3.6/site-packages/patsy/desc.py in from_formula(cls, tree_or_string)
    162             tree = tree_or_string
    163         else:
--> 164             tree = parse_formula(tree_or_string)
    165         value = Evaluator().eval(tree, require_evalexpr=False)
    166         assert isinstance(value, cls)

~/anaconda3/lib/python3.6/site-packages/patsy/parse_formula.py in parse_formula(code, extra_operators)
    146     tree = infix_parse(_tokenize_formula(code, operator_strings),
    147                        operators,
--> 148                        _atomic_token_types)
    149     if not isinstance(tree, ParseNode) or tree.type != "~":
    150         tree = ParseNode("~", None, [tree], tree.origin)

~/anaconda3/lib/python3.6/site-packages/patsy/infix_parser.py in infix_parse(tokens, operators, atomic_types, trace)
    208 
    209     want_noun = True
--> 210     for token in token_source:
    211         if c.trace:
    212             print("Reading next token (want_noun=%r)" % (want_noun,))

~/anaconda3/lib/python3.6/site-packages/patsy/parse_formula.py in _tokenize_formula(code, operator_strings)
     92         else:
     93             it.push_back((pytype, token_string, origin))
---> 94             yield _read_python_expr(it, end_tokens)
     95 
     96 def test__tokenize_formula():

~/anaconda3/lib/python3.6/site-packages/patsy/parse_formula.py in _read_python_expr(it, end_tokens)
     42     origins = []
     43     bracket_level = 0
---> 44     for pytype, token_string, origin in it:
     45         assert bracket_level >= 0
     46         if bracket_level == 0 and token_string in end_tokens:

~/anaconda3/lib/python3.6/site-packages/patsy/util.py in next(self)
    330         else:
    331             # May raise StopIteration
--> 332             return six.advance_iterator(self._it)
    333     __next__ = next
    334 

~/anaconda3/lib/python3.6/site-packages/patsy/tokens.py in python_tokenize(code)
     33                 break
     34             origin = Origin(code, start, end)
---> 35             assert pytype not in (tokenize.NL, tokenize.NEWLINE)
     36             if pytype == tokenize.ERRORTOKEN:
     37                 raise PatsyError("error tokenizing input "

AssertionError:
statease / dexpy

Coffee Example raises PatsyError #58
