Fix small factual error.
diff --git a/Doc/api/abstract.tex b/Doc/api/abstract.tex
index 1acbef9..f19928f 100644
--- a/Doc/api/abstract.tex
+++ b/Doc/api/abstract.tex
@@ -342,7 +342,7 @@
\begin{cfuncdesc}{int}{PyObject_Length}{PyObject *o}
\cfuncline{int}{PyObject_Size}{PyObject *o}
Return the length of object \var{o}. If the object \var{o} provides
- both sequence and mapping protocols, the sequence length is
+ either the sequence and mapping protocols, the sequence length is
returned. On error, \code{-1} is returned. This is the equivalent
to the Python expression \samp{len(\var{o})}.\bifuncindex{len}
\end{cfuncdesc}