From 14a95449ca041e72e3a51d5bfc55e03f6acbb730 Mon Sep 17 00:00:00 2001
From: Scott Sanderson <ssanderson@quantopian.com>
Date: Fri, 12 Aug 2016 13:09:04 -0400
Subject: [PATCH] DOC: Clarify how AssetExists() is special.

---
 zipline/pipeline/term.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/zipline/pipeline/term.py b/zipline/pipeline/term.py
index 4174f495..95b444d2 100644
--- a/zipline/pipeline/term.py
+++ b/zipline/pipeline/term.py
@@ -320,6 +320,9 @@ class AssetExists(Term):
     every asset on every date.  We don't subclass Filter, however, because
     `AssetExists` is computed directly by the PipelineEngine.
 
+    This term is guaranteed to be available as an input for any term computed
+    by SimplePipelineEngine.run_pipeline().
+
     See Also
     --------
     zipline.assets.AssetFinder.lifetimes