+ifneq ($(shell $(SPHINXBUILD) 2> /dev/null; echo $$?), 0)
+The 'sphinx-build' command was not found. Make sure you have Sphinx
+installed, then set the SPHINXBUILD environment variable to point
+to the full path of the 'sphinx-build' executable. Alternatively you
+may add the Sphinx directory to PATH.
+If you don't have Sphinx installed, grab it from
PAPEROPT_a4 = -D latex_paper_size=a4
PAPEROPT_letter = -D latex_paper_size=letter