Greetings,

Would you happen to know what causes this error while trying to run the Otto example? It manages to initialize the problem but produces the error as it transitions to maximize the function. I'm running the anaconda distribution with python 3.6.

`Initialization

Step | Time | Value | colsample_bytree | gamma | learning_rate | max_delta_step | max_depth | min_child_weight | n_estimators | subsample |

1 | 06m06s |   -0.32531 |             0.6182 |    0.9051 |          0.2812 |           0.0129 |      8.4669 |             2.6626 |       944.8025 |      0.7061 | 

2 | 02m56s |   -0.27711 |             0.7733 |    0.6258 |          0.1907 |           0.0931 |      5.4166 |             6.0346 |       616.8563 |      0.7488 | 

3 | 06m30s |   -0.28382 |             0.8422 |    0.0806 |          0.2088 |           0.0239 |      9.3391 |             5.7449 |       749.8462 |      0.7838 | 

4 | 06m32s |   -0.27949 |             0.9063 |    0.1119 |          0.2483 |           0.0400 |      8.9312 |             4.4974 |       801.3183 |      0.7566 | 

5 | 00m37s |   -0.44748 |             0.9505 |    0.6875 |          0.1109 |           0.0882 |      5.9782 |             5.9778 |       117.2441 |      0.7775 | 

IndexError Traceback (most recent call last)
in ()
71 })
72
---> 73 xgboostBO.maximize()
74 print('-'*53)
75

/home/ron/software/anaconda3/lib/python3.6/site-packages/bayes_opt/bayesian_optimization.py in maximize(self, init_points, n_iter, acq, kappa, xi, **gp_params)
262 gp=self.gp,
263 y_max=y_max,
--> 264 bounds=self.bounds)
265
266 # Print new header

/home/ron/software/anaconda3/lib/python3.6/site-packages/bayes_opt/helpers.py in acq_max(ac, gp, y_max, bounds)
53
54 # Store it if better than previous minimum(maximum).
---> 55 if max_acq is None or -res.fun[0] >= max_acq:
56 x_max = res.x
57 max_acq = -res.fun[0]

IndexError: too many indices for array`