This is used by `treesit-language-at', which is used by various
functions to determine which parser to use at point.
-The function is called with one argument, the position of point.")
+The function is called with one argument, the position of point.
+
+In general, this function should call `treesit-node-at' with an
+explicit language (usually the host language), and determine the
+language at point using the type of the returned node.
+
+DO NOT derive the language at point from parser ranges. It's
+cumbersome and can't deal with some edge cases.")
(defun treesit-language-at (position)
"Return the language at POSITION.