Clarify docs for functions taking bytes and not str.
diff --git a/.gitignore b/.gitignore
index c444c17..979fd44 100644
--- a/.gitignore
+++ b/.gitignore
@@ -27,6 +27,7 @@
*.py[co]
*.egg-info
*~
+.*.swp
.DS_Store
/dist
/build
diff --git a/docs/advanced/cast/strings.rst b/docs/advanced/cast/strings.rst
index 2cdbade..e25701e 100644
--- a/docs/advanced/cast/strings.rst
+++ b/docs/advanced/cast/strings.rst
@@ -58,7 +58,9 @@
--------------------
A Python ``bytes`` object will be passed to C++ functions that accept
-``std::string`` or ``char*`` *without* conversion.
+``std::string`` or ``char*`` *without* conversion. On Python 3, in order to
+make a function *only* accept ``bytes`` (and not ``str``), declare it as taking
+a ``py::bytes`` argument.
Returning C++ strings to Python