Add API for static strings, primarily good for identifiers.
Thanks to Konrad Schöbel and Jasper Schulz for helping with the mass-editing.
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index 2bf8933..a16d13c 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -128,6 +128,7 @@
 static PyObject *
 fileio_close(fileio *self)
 {
+    _Py_identifier(close);
     if (!self->closefd) {
         self->fd = -1;
         Py_RETURN_NONE;
@@ -143,8 +144,8 @@
     if (errno < 0)
         return NULL;
 
-    return PyObject_CallMethod((PyObject*)&PyRawIOBase_Type,
-                               "close", "O", self);
+    return _PyObject_CallMethodId((PyObject*)&PyRawIOBase_Type,
+                                  &PyId_close, "O", self);
 }
 
 static PyObject *