Remove trailing whitespace.
diff --git a/Doc/library/math.rst b/Doc/library/math.rst
index 1e9611e..f171ec1 100644
--- a/Doc/library/math.rst
+++ b/Doc/library/math.rst
@@ -98,7 +98,7 @@
 .. function:: isnan(x)
 
    Checks if the float *x* is a NaN (not a number). NaNs are part of the
-   IEEE 754 standards. Operation like but not limited to ``inf * 0``, 
+   IEEE 754 standards. Operation like but not limited to ``inf * 0``,
    ``inf / inf`` or any operation involving a NaN, e.g. ``nan * 1``, return
    a NaN.