Make PyUnicode_Copy() private => _PyUnicode_Copy()
Undocument the function.
Make also decode_utf8_errors() as private (static).
diff --git a/Include/unicodeobject.h b/Include/unicodeobject.h
index be45b02..235c677 100644
--- a/Include/unicodeobject.h
+++ b/Include/unicodeobject.h
@@ -616,9 +616,11 @@
#endif
/* Get a copy of a Unicode string. */
-PyAPI_FUNC(PyObject*) PyUnicode_Copy(
+#ifndef Py_LIMITED_API
+PyAPI_FUNC(PyObject*) _PyUnicode_Copy(
PyObject *unicode
);
+#endif
/* Copy character from one unicode object into another, this function performs
character conversion when necessary and falls back to memcpy if possible.