SF bug #821701: reduce docs neglect a very important piece of information.
Add a note showing which argument is the accumulator.
diff --git a/Doc/lib/libfuncs.tex b/Doc/lib/libfuncs.tex
index 936a023..a9f3a65 100644
--- a/Doc/lib/libfuncs.tex
+++ b/Doc/lib/libfuncs.tex
@@ -816,7 +816,9 @@
Apply \var{function} of two arguments cumulatively to the items of
\var{sequence}, from left to right, so as to reduce the sequence to
a single value. For example, \code{reduce(lambda x, y: x+y, [1, 2,
- 3, 4, 5])} calculates \code{((((1+2)+3)+4)+5)}. If the optional
+ 3, 4, 5])} calculates \code{((((1+2)+3)+4)+5)}. The left argument,
+ \var{x}, is the accumulated value and the right argument, \var{y},
+ is the update value from the \var{sequence}. If the optional
\var{initializer} is present, it is placed before the items of the
sequence in the calculation, and serves as a default when the
sequence is empty. If \var{initializer} is not given and