DOC: add Python 3 note to Colab install instructions
@@ -130,6 +130,11 @@ indexed in the left panel, or check out the :ref:`example-gallery` for more idea
Quick Start: Altair + Colab
---------------------------
+.. note::
+
+ Altair version 2.0 requires Python 3.5 or later.
+ It does not work with Python 2.
+
Altair can be used directly in Google's Colab_. Open a notebook, and run the
following in a notebook cell:
