Added try except ImportError for collections.abc which will require a…

… change from Python 3.8. Style follows similar usage elsewhere in deep.

Also easy to drop try/except when Python 2.7 may not be supported in the future.

deap/base.py

@@ -20,7 +20,11 @@ class used as base class, for the fitness member of any individual. """
 
 import sys
 
-from collections import Sequence
+try:
+    from collections.abc import Sequence
+except ImportError:
+    from collections import Sequence
+
 from copy import deepcopy
 from functools import partial
 from operator import mul, truediv

deap/benchmarks/movingpeaks.py

@@ -24,7 +24,11 @@
 import math
 import itertools
 import random
-from collections import Sequence
+
+try:
+    from collections.abc import Sequence
+except:
+    from colections import Sequence
 
 def cone(individual, position, height, width):
     """The cone peak function to be used with scenario 2 and 3.

deap/tools/constraint.py

@@ -1,7 +1,11 @@
 
 from functools import wraps
 from itertools import repeat
-from collections import Sequence
+
+try:
+    from collections.abc import Sequence
+except ImportError:
+    from collections import Sequence
 
 class DeltaPenalty(object):
     """This decorator returns penalized fitness for invalid individuals and the

deap/tools/crossover.py

@@ -2,7 +2,11 @@
 import random
 import warnings
 
-from collections import Sequence
+try:
+    from collections.abc import Sequence
+except ImportError:
+    from collections import Sequence
+
 from itertools import repeat
 
 

deap/tools/mutation.py

@@ -3,8 +3,11 @@
 import random
 
 from itertools import repeat
-from collections import Sequence
 
+try:
+    from collections.abc import Sequence
+except ImportError:
+    from collections import Sequence
 
 ######################################
 # GA Mutations                       #