RF: Use abc instead of collections, fix docstring

fsleyes_props/properties_types.py

@@ -33,7 +33,7 @@ added as attributes of a :class:`.HasProperties` class definition.
 
 import os.path as op
 
-import collections
+from collections import abc
 
 import six
 
@@ -798,7 +798,7 @@ class Colour(props.PropertyBase):
         """
         props.PropertyBase.validate(self, instance, attributes, value)
 
-        if (not isinstance(value, collections.Sequence)) or \
+        if (not isinstance(value, abc.Sequence)) or \
            (len(value) not in (3, 4)):
             raise ValueError('Colour must be a sequence of three/four values')
 

fsleyes_props/properties_value.py

@@ -1178,7 +1178,7 @@ class PropertyValueList(PropertyValue):
 
 
     def move(self, from_, to):
-        """Move the item from 'from\_' to 'to'."""
+        """Move the item from ``from_`` to ``to``."""
 
         propVals = self.getPropertyValueList()
         propVals.insert(to, propVals.pop(from_))

fsleyes_props/widgets.py

@@ -98,7 +98,7 @@ import sys
 import os
 import os.path as op
 
-from collections import Iterable
+from collections.abc import Iterable
 
 import six