diff --git a/nac3core/src/type_check/mod.rs b/nac3core/src/type_check/mod.rs
index dfad981a..c8e4943f 100644
--- a/nac3core/src/type_check/mod.rs
+++ b/nac3core/src/type_check/mod.rs
@@ -5,3 +5,5 @@ mod magic_methods;
 pub mod primitives;
 pub mod statement_check;
 pub mod typedef;
+pub mod signature;
+
diff --git a/nac3core/src/type_check/primitives.rs b/nac3core/src/type_check/primitives.rs
index 0aa076dd..cf290006 100644
--- a/nac3core/src/type_check/primitives.rs
+++ b/nac3core/src/type_check/primitives.rs
@@ -2,6 +2,8 @@ use super::context::*;
 use super::typedef::{TypeEnum::*, *};
 use std::collections::HashMap;
 
+pub const PRIMITIVES: [&str; 6] = ["int32", "int64", "float", "bool", "list", "tuple"];
+
 pub const TUPLE_TYPE: ParamId = ParamId(0);
 pub const LIST_TYPE: ParamId = ParamId(1);
 
diff --git a/nac3core/src/type_check/signature.rs b/nac3core/src/type_check/signature.rs
new file mode 100644
index 00000000..04d3fc4b
--- /dev/null
+++ b/nac3core/src/type_check/signature.rs
@@ -0,0 +1,121 @@
+/// obtain class and function signature from AST
+use super::primitives::PRIMITIVES;
+use rustpython_parser::ast::{ExpressionType, Statement, StatementType, StringGroup};
+
+fn typename_from_expr<'b: 'a, 'a>(typenames: &mut Vec<&'a str>, expr: &'b ExpressionType) {
+    match expr {
+        ExpressionType::Identifier { name } => typenames.push(&name),
+        ExpressionType::String { value } => match value {
+            StringGroup::Constant { value } => typenames.push(&value),
+            _ => unimplemented!(),
+        },
+        ExpressionType::Subscript { a, b } => {
+            typename_from_expr(typenames, &b.node);
+            typename_from_expr(typenames, &a.node)
+        }
+        _ => unimplemented!(),
+    }
+}
+
+fn typename_from_fn<'b: 'a, 'a>(typenames: &mut Vec<&'a str>, fun: &'b StatementType) {
+    match fun {
+        StatementType::FunctionDef { args, returns, .. } => {
+            for arg in args.args.iter() {
+                if let Some(ann) = &arg.annotation {
+                    typename_from_expr(typenames, &ann.node);
+                }
+            }
+            if let Some(returns) = &returns {
+                typename_from_expr(typenames, &returns.node);
+            }
+        }
+        _ => unreachable!(),
+    }
+}
+
+pub fn resolve_classes<'b: 'a, 'a>(stmts: &'b [Statement]) -> (Vec<&'a str>, Vec<&'a str>) {
+    let mut classes = Vec::new();
+    let mut typenames = Vec::new();
+    for stmt in stmts.iter() {
+        match &stmt.node {
+            StatementType::ClassDef {
+                name, body, bases, ..
+            } => {
+                // check if class is not duplicated...
+                // and annotations
+                classes.push(&name[..]);
+                for base in bases.iter() {
+                    let name = match &base.node {
+                        ExpressionType::Identifier { name } => name,
+                        ExpressionType::String { value } => match value {
+                            StringGroup::Constant { value } => value,
+                            _ => unimplemented!(),
+                        },
+                        _ => unimplemented!(),
+                    };
+                    typenames.push(&name[..]);
+                }
+                // may check if fields/functions are not duplicated
+                for stmt in body.iter() {
+                    match &stmt.node {
+                        StatementType::AnnAssign { annotation, .. } => {
+                            typename_from_expr(&mut typenames, &annotation.node)
+                        }
+                        StatementType::FunctionDef { .. } => {
+                            typename_from_fn(&mut typenames, &stmt.node);
+                        }
+                        _ => unimplemented!(),
+                    }
+                }
+            }
+            StatementType::FunctionDef { .. } => {
+                // may check annotations
+                typename_from_fn(&mut typenames, &stmt.node);
+            }
+            _ => (),
+        }
+    }
+    let mut unknowns = Vec::new();
+    for n in typenames {
+        if !PRIMITIVES.contains(&n) && !classes.contains(&n) && !unknowns.contains(&n) {
+            unknowns.push(n);
+        }
+    }
+    (classes, unknowns)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use indoc::indoc;
+    use rustpython_parser::parser::parse_program;
+
+    #[test]
+    fn test_get_classes() {
+        let ast = parse_program(indoc! {"
+            class Foo:
+                a: int32
+                b: Test
+
+                def test(self, a: int32) -> Test2:
+                    return b
+
+            class Bar(Foo, 'FooBar'):
+                def test2(self, a: list[Foo]) -> Test2:
+                    return b
+
+                def test3(self, a: list[FooBar2]) -> Test2:
+                    return b
+        " })
+        .unwrap();
+        let (mut classes, mut unknowns) = resolve_classes(&ast.statements);
+        let classes_count = classes.len();
+        let unknowns_count = unknowns.len();
+        classes.sort();
+        unknowns.sort();
+        assert_eq!(classes.len(), classes_count);
+        assert_eq!(unknowns.len(), unknowns_count);
+        assert_eq!(&classes, &["Bar", "Foo"]);
+        assert_eq!(&unknowns, &["FooBar", "FooBar2", "Test", "Test2"]);
+    }
+}