add matrix multiplication operator support to 2to3
diff --git a/Lib/lib2to3/pgen2/grammar.py b/Lib/lib2to3/pgen2/grammar.py
index 1aa5c43..8220b0a 100644
--- a/Lib/lib2to3/pgen2/grammar.py
+++ b/Lib/lib2to3/pgen2/grammar.py
@@ -151,6 +151,7 @@
 { LBRACE
 } RBRACE
 @ AT
+@= ATEQUAL
 == EQEQUAL
 != NOTEQUAL
 <> NOTEQUAL