Tweaked _initial_key KeyError exception message
@@ -610,7 +610,7 @@ class DynamicMap(HoloMap):
else:
undefined.append(kdim)
if undefined:
- msg = ('Dimensions {undefined_dims} do not specify range or values needed '
+ msg = ('Dimension(s) {undefined_dims} do not specify range or values needed '
'to generate initial key')
undefined_dims = ', '.join(['%r' % str(dim) for dim in undefined])
raise KeyError(msg.format(undefined_dims=undefined_dims))
