diff --git a/tests/snippets/bools.py b/tests/snippets/bools.py
index 2aa817ca4..0c277143b 100644
--- a/tests/snippets/bools.py
+++ b/tests/snippets/bools.py
@@ -16,6 +16,9 @@ assert bool() == False
 assert bool(1) == True
 assert bool({}) == False
 
+assert bool(NotImplemented) == True
+assert bool(...) == True
+
 if not 1:
     raise BaseException
 
diff --git a/vm/src/frame.rs b/vm/src/frame.rs
index 3186ae564..4fd7ae687 100644
--- a/vm/src/frame.rs
+++ b/vm/src/frame.rs
@@ -580,18 +580,15 @@ impl Frame {
             }
             bytecode::Instruction::PrintExpr => {
                 let expr = self.pop_value();
-                match expr.payload {
-                    PyObjectPayload::None => (),
-                    _ => {
-                        let repr = vm.to_repr(&expr)?;
-                        builtins::builtin_print(
-                            vm,
-                            PyFuncArgs {
-                                args: vec![repr],
-                                kwargs: vec![],
-                            },
-                        )?;
-                    }
+                if !expr.is(&vm.get_none()) {
+                    let repr = vm.to_repr(&expr)?;
+                    builtins::builtin_print(
+                        vm,
+                        PyFuncArgs {
+                            args: vec![repr],
+                            kwargs: vec![],
+                        },
+                    )?;
                 }
                 Ok(None)
             }
diff --git a/vm/src/obj/objbool.rs b/vm/src/obj/objbool.rs
index 0f272d171..09e0759c7 100644
--- a/vm/src/obj/objbool.rs
+++ b/vm/src/obj/objbool.rs
@@ -17,7 +17,7 @@ impl IntoPyObject for bool {
     }
 }
 
-pub fn boolval(vm: &mut VirtualMachine, obj: PyObjectRef) -> Result<bool, PyObjectRef> {
+pub fn boolval(vm: &mut VirtualMachine, obj: PyObjectRef) -> PyResult<bool> {
     if let Some(s) = obj.payload::<PyString>() {
         return Ok(!s.value.is_empty());
     }
@@ -32,7 +32,6 @@ pub fn boolval(vm: &mut VirtualMachine, obj: PyObjectRef) -> Result<bool, PyObje
     }
     let result = match obj.payload {
         PyObjectPayload::Sequence { ref elements } => !elements.borrow().is_empty(),
-        PyObjectPayload::None { .. } => false,
         _ => {
             if let Ok(f) = vm.get_method(obj.clone(), "__bool__") {
                 let bool_res = vm.invoke(f, PyFuncArgs::default())?;
diff --git a/vm/src/obj/objnone.rs b/vm/src/obj/objnone.rs
index 2aceea915..bc94f9cb9 100644
--- a/vm/src/obj/objnone.rs
+++ b/vm/src/obj/objnone.rs
@@ -5,6 +5,7 @@ pub fn init(context: &PyContext) {
     let none_type = &context.none.typ();
     context.set_attr(&none_type, "__new__", context.new_rustfunc(none_new));
     context.set_attr(&none_type, "__repr__", context.new_rustfunc(none_repr));
+    context.set_attr(&none_type, "__bool__", context.new_rustfunc(none_bool));
 }
 
 fn none_new(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
@@ -20,3 +21,8 @@ fn none_repr(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(vm, args, required = [(_zelf, Some(vm.ctx.none().typ()))]);
     Ok(vm.ctx.new_str("None".to_string()))
 }
+
+fn none_bool(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
+    arg_check!(vm, args, required = [(_zelf, Some(vm.ctx.none().typ()))]);
+    Ok(vm.ctx.new_bool(false))
+}
diff --git a/vm/src/obj/objstr.rs b/vm/src/obj/objstr.rs
index 4ee7f38f5..6d9d622d0 100644
--- a/vm/src/obj/objstr.rs
+++ b/vm/src/obj/objstr.rs
@@ -4,8 +4,8 @@ use super::objtype;
 use crate::format::{FormatParseError, FormatPart, FormatString};
 use crate::function::PyRef;
 use crate::pyobject::{
-    IntoPyObject, OptArg, PyContext, PyFuncArgs, PyIterable, PyObjectPayload, PyObjectPayload2,
-    PyObjectRef, PyResult, TypeProtocol,
+    IntoPyObject, OptionalArg, PyContext, PyFuncArgs, PyIterable, PyObjectPayload,
+    PyObjectPayload2, PyObjectRef, PyResult, TypeProtocol,
 };
 use crate::vm::VirtualMachine;
 use num_traits::ToPrimitive;
@@ -160,24 +160,24 @@ impl PyStringRef {
     fn endswith(
         self,
         suffix: PyStringRef,
-        start: OptArg<usize>,
-        end: OptArg<usize>,
+        start: OptionalArg<usize>,
+        end: OptionalArg<usize>,
         _vm: &mut VirtualMachine,
     ) -> bool {
-        let start = start.unwrap_or(0);
-        let end = end.unwrap_or(self.value.len());
+        let start = start.into_option().unwrap_or(0);
+        let end = end.into_option().unwrap_or(self.value.len());
         self.value[start..end].ends_with(&suffix.value)
     }
 
     fn startswith(
         self,
         prefix: PyStringRef,
-        start: OptArg<usize>,
-        end: OptArg<usize>,
+        start: OptionalArg<usize>,
+        end: OptionalArg<usize>,
         _vm: &mut VirtualMachine,
     ) -> bool {
-        let start = start.unwrap_or(0);
-        let end = end.unwrap_or(self.value.len());
+        let start = start.into_option().unwrap_or(0);
+        let end = end.into_option().unwrap_or(self.value.len());
         self.value[start..end].starts_with(&prefix.value)
     }
 
diff --git a/vm/src/pyobject.rs b/vm/src/pyobject.rs
index 9ab66373a..a296ea32d 100644
--- a/vm/src/pyobject.rs
+++ b/vm/src/pyobject.rs
@@ -156,7 +156,9 @@ pub struct PyContext {
 
 fn _nothing() -> PyObjectRef {
     PyObject {
-        payload: PyObjectPayload::None,
+        payload: PyObjectPayload::AnyRustValue {
+            value: Box::new(()),
+        },
         typ: None,
     }
     .into_ref()
@@ -224,14 +226,23 @@ impl PyContext {
         let exceptions = exceptions::ExceptionZoo::new(&type_type, &object_type, &dict_type);
 
         let none = PyObject::new(
-            PyObjectPayload::None,
+            PyObjectPayload::AnyRustValue {
+                value: Box::new(()),
+            },
             create_type("NoneType", &type_type, &object_type, &dict_type),
         );
 
-        let ellipsis = PyObject::new(PyObjectPayload::None, ellipsis_type.clone());
+        let ellipsis = PyObject::new(
+            PyObjectPayload::AnyRustValue {
+                value: Box::new(()),
+            },
+            ellipsis_type.clone(),
+        );
 
         let not_implemented = PyObject::new(
-            PyObjectPayload::NotImplemented,
+            PyObjectPayload::AnyRustValue {
+                value: Box::new(()),
+            },
             create_type("NotImplementedType", &type_type, &object_type, &dict_type),
         );
 
@@ -1214,17 +1225,26 @@ where
     }
 }
 
-pub struct OptArg<T>(Option<T>);
+/// An argument that may or may not be provided by the caller.
+///
+/// This style of argument is not possible in pure Python.
+pub enum OptionalArg<T> {
+    Present(T),
+    Missing,
+}
 
-impl<T> std::ops::Deref for OptArg<T> {
-    type Target = Option<T>;
+use self::OptionalArg::*;
 
-    fn deref(&self) -> &Option<T> {
-        &self.0
+impl<T> OptionalArg<T> {
+    pub fn into_option(self) -> Option<T> {
+        match self {
+            Present(value) => Some(value),
+            Missing => None,
+        }
     }
 }
 
-impl<T> FromArgs for OptArg<T>
+impl<T> FromArgs for OptionalArg<T>
 where
     T: TryFromObject,
 {
@@ -1239,16 +1259,16 @@ where
     where
         I: Iterator<Item = PyArg>,
     {
-        Ok(OptArg(if let Some(PyArg::Positional(_)) = args.peek() {
+        Ok(if let Some(PyArg::Positional(_)) = args.peek() {
             let value = if let Some(PyArg::Positional(value)) = args.next() {
                 value
             } else {
                 unreachable!()
             };
-            Some(T::try_from_object(vm, value)?)
+            Present(T::try_from_object(vm, value)?)
         } else {
-            None
-        }))
+            Missing
+        })
     }
 }
 
@@ -1499,8 +1519,6 @@ pub enum PyObjectPayload {
         name: String,
         scope: ScopeRef,
     },
-    None,
-    NotImplemented,
     Class {
         name: String,
         dict: RefCell<PyAttributes>,
@@ -1540,8 +1558,6 @@ impl fmt::Debug for PyObjectPayload {
                 ref object,
             } => write!(f, "bound-method: {:?} of {:?}", function, object),
             PyObjectPayload::Module { .. } => write!(f, "module"),
-            PyObjectPayload::None => write!(f, "None"),
-            PyObjectPayload::NotImplemented => write!(f, "NotImplemented"),
             PyObjectPayload::Class { ref name, .. } => write!(f, "class {:?}", name),
             PyObjectPayload::Instance { .. } => write!(f, "instance"),
             PyObjectPayload::RustFunction { .. } => write!(f, "rust function"),
diff --git a/vm/src/stdlib/json.rs b/vm/src/stdlib/json.rs
index 7403c8d8c..0d0bc23dc 100644
--- a/vm/src/stdlib/json.rs
+++ b/vm/src/stdlib/json.rs
@@ -11,7 +11,7 @@ use crate::obj::{
     objtype,
 };
 use crate::pyobject::{
-    create_type, DictProtocol, PyContext, PyFuncArgs, PyObjectPayload, PyObjectRef, PyResult,
+    create_type, DictProtocol, IdProtocol, PyContext, PyFuncArgs, PyObjectRef, PyResult,
     TypeProtocol,
 };
 use crate::VirtualMachine;
@@ -69,7 +69,7 @@ impl<'s> serde::Serialize for PyObjectSerializer<'s> {
                 map.serialize_entry(&key, &self.clone_with_object(&e.1))?;
             }
             map.end()
-        } else if let PyObjectPayload::None = self.pyobject.payload {
+        } else if self.pyobject.is(&self.vm.get_none()) {
             serializer.serialize_none()
         } else {
             Err(serde::ser::Error::custom(format!(
diff --git a/vm/src/vm.rs b/vm/src/vm.rs
index 709a9f46c..e3d06d5fa 100644
--- a/vm/src/vm.rs
+++ b/vm/src/vm.rs
@@ -444,10 +444,12 @@ impl VirtualMachine {
         // Add missing positional arguments, if we have fewer positional arguments than the
         // function definition calls for
         if nargs < nexpected_args {
-            let available_defaults = match defaults.payload {
-                PyObjectPayload::Sequence { ref elements } => elements.borrow().clone(),
-                PyObjectPayload::None => vec![],
-                _ => panic!("function defaults not tuple or None"),
+            let available_defaults = if defaults.is(&self.get_none()) {
+                vec![]
+            } else if let PyObjectPayload::Sequence { ref elements } = defaults.payload {
+                elements.borrow().clone()
+            } else {
+                panic!("function defaults not tuple or None");
             };
 
             // Given the number of defaults available, check all the arguments for which we