check ifinstance(x, Iterable) instead of having __iter__

and order imports according to PEP8

Author: basnijholt

adaptive/learner/skopt_learner.py

@@ -1,8 +1,9 @@
 # -*- coding: utf-8 -*-
 
+import collections
+
 import numpy as np
 from skopt import Optimizer
-from collections import OrderedDict
 
 from adaptive.learner.base_learner import BaseLearner
 from adaptive.notebook_integration import ensure_holoviews
@@ -27,11 +28,11 @@ class SKOptLearner(Optimizer, BaseLearner):
     def __init__(self, function, **kwargs):
         self.function = function
         self.pending_points = set()
-        self.data = OrderedDict()
+        self.data = collections.OrderedDict()
         super().__init__(**kwargs)
 
     def tell(self, x, y, fit=True):
-        if hasattr(x, "__iter__"):
+        if isinstance(x, collections.abc.Iterable):
             self.pending_points.discard(tuple(x))
             self.data[tuple(x)] = y
             super().tell(x, y, fit)