Add context manager functions to file

rt/include/python/builtins.hpp

@@ -163,7 +163,17 @@ struct {
     type(int fd = -1, size_t len = 0) : fd(fd), len(len) {}
 
     type(const type &other)
-        : fd(other.fd), len(other.len), read(this), close(this) {}
+        : read(this), write(this), close(this), flush(this), py_enter(this),
+          py_exit(this), fd(other.fd), len(other.len) {}
+
+    METHOD(
+        type, py_enter, (), const { return *self; })
+
+    METHOD(
+        typon::Task<bool>, py_exit, (), const {
+          co_await self->close();
+          co_return true;
+        })
 
     int fd;
     size_t len;