diff --git a/python/src/lib.rs b/python/src/lib.rs
index 26be624..7eafa43 100644
--- a/python/src/lib.rs
+++ b/python/src/lib.rs
@@ -4,6 +4,7 @@ mod decoder;
 mod enums;
 mod geo;
 mod ifd;
+mod reader;
 mod thread_pool;
 mod tiff;
 mod tile;
diff --git a/python/src/reader/aiohttp.rs b/python/src/reader/aiohttp.rs
new file mode 100644
index 0000000..3f9e4a7
--- /dev/null
+++ b/python/src/reader/aiohttp.rs
@@ -0,0 +1,28 @@
+use pyo3::exceptions::PyTypeError;
+use pyo3::intern;
+use pyo3::prelude::*;
+use pyo3::pybacked::PyBackedStr;
+
+struct AiohttpSession(PyObject);
+
+impl<'py> FromPyObject<'py> for AiohttpSession {
+    fn extract_bound(ob: &Bound<'py, PyAny>) -> PyResult<Self> {
+        let py = ob.py();
+        let cls = ob.getattr(intern!(py, "__class__"))?;
+        let module = cls
+            .getattr(intern!(py, "__module__"))?
+            .extract::<PyBackedStr>()?;
+        let class_name = cls
+            .getattr(intern!(py, "__name__"))?
+            .extract::<PyBackedStr>()?;
+        if module.starts_with("aiohttp") && class_name == "ClientSession" {
+            todo!()
+        } else {
+            let msg = format!(
+                "Expected aiohttp.ClientSession, got {}.{}",
+                module, class_name
+            );
+            Err(PyTypeError::new_err(msg))
+        }
+    }
+}
diff --git a/python/src/reader/mod.rs b/python/src/reader/mod.rs
new file mode 100644
index 0000000..d6640bb
--- /dev/null
+++ b/python/src/reader/mod.rs
@@ -0,0 +1 @@
+mod aiohttp;