diff --git a/crates/ruff_python_ast/src/function.rs b/crates/ruff_python_ast/src/function.rs
new file mode 100644
index 0000000000..1f7f114f69
--- /dev/null
+++ b/crates/ruff_python_ast/src/function.rs
@@ -0,0 +1,114 @@
+use crate::node::AnyNodeRef;
+use ruff_text_size::TextRange;
+use rustpython_ast::{
+    Arguments, Expr, Identifier, Ranged, StmtAsyncFunctionDef, StmtFunctionDef, Suite,
+};
+
+/// Enum that represents any python function definition.
+#[derive(Copy, Clone, PartialEq, Debug)]
+pub enum AnyFunctionDefinition<'a> {
+    FunctionDefinition(&'a StmtFunctionDef),
+    AsyncFunctionDefinition(&'a StmtAsyncFunctionDef),
+}
+
+impl<'a> AnyFunctionDefinition<'a> {
+    pub const fn cast_ref(reference: AnyNodeRef<'a>) -> Option<Self> {
+        match reference {
+            AnyNodeRef::StmtAsyncFunctionDef(definition) => {
+                Some(Self::AsyncFunctionDefinition(definition))
+            }
+            AnyNodeRef::StmtFunctionDef(definition) => Some(Self::FunctionDefinition(definition)),
+            _ => None,
+        }
+    }
+
+    /// Returns `Some` if this is a [`StmtFunctionDef`] and `None` otherwise.
+    pub const fn as_function_definition(self) -> Option<&'a StmtFunctionDef> {
+        if let Self::FunctionDefinition(definition) = self {
+            Some(definition)
+        } else {
+            None
+        }
+    }
+
+    /// Returns `Some` if this is a [`StmtAsyncFunctionDef`] and `None` otherwise.
+    pub const fn as_async_function_definition(self) -> Option<&'a StmtAsyncFunctionDef> {
+        if let Self::AsyncFunctionDefinition(definition) = self {
+            Some(definition)
+        } else {
+            None
+        }
+    }
+
+    /// Returns the function's name
+    pub const fn name(self) -> &'a Identifier {
+        match self {
+            Self::FunctionDefinition(definition) => &definition.name,
+            Self::AsyncFunctionDefinition(definition) => &definition.name,
+        }
+    }
+
+    /// Returns the function arguments (parameters).
+    pub fn arguments(self) -> &'a Arguments {
+        match self {
+            Self::FunctionDefinition(definition) => definition.args.as_ref(),
+            Self::AsyncFunctionDefinition(definition) => definition.args.as_ref(),
+        }
+    }
+
+    /// Returns the function's body
+    pub const fn body(self) -> &'a Suite {
+        match self {
+            Self::FunctionDefinition(definition) => &definition.body,
+            Self::AsyncFunctionDefinition(definition) => &definition.body,
+        }
+    }
+
+    /// Returns the decorators attributing the function.
+    pub fn decorators(self) -> &'a [Expr] {
+        match self {
+            Self::FunctionDefinition(definition) => &definition.decorator_list,
+            Self::AsyncFunctionDefinition(definition) => &definition.decorator_list,
+        }
+    }
+
+    pub fn returns(self) -> Option<&'a Expr> {
+        match self {
+            Self::FunctionDefinition(definition) => definition.returns.as_deref(),
+            Self::AsyncFunctionDefinition(definition) => definition.returns.as_deref(),
+        }
+    }
+
+    pub fn type_comments(self) -> Option<&'a str> {
+        match self {
+            Self::FunctionDefinition(definition) => definition.type_comment.as_deref(),
+            Self::AsyncFunctionDefinition(definition) => definition.type_comment.as_deref(),
+        }
+    }
+
+    /// Returns `true` if this is [`Self::AsyncFunctionDefinition`]
+    pub const fn is_async(self) -> bool {
+        matches!(self, Self::AsyncFunctionDefinition(_))
+    }
+}
+
+impl Ranged for AnyFunctionDefinition<'_> {
+    fn range(&self) -> TextRange {
+        match self {
+            AnyFunctionDefinition::FunctionDefinition(definition) => definition.range(),
+            AnyFunctionDefinition::AsyncFunctionDefinition(definition) => definition.range(),
+        }
+    }
+}
+
+impl<'a> From<&'a StmtFunctionDef> for AnyFunctionDefinition<'a> {
+    fn from(value: &'a StmtFunctionDef) -> Self {
+        Self::FunctionDefinition(value)
+    }
+}
+
+impl<'a> From<&'a StmtAsyncFunctionDef> for AnyFunctionDefinition<'a> {
+    fn from(value: &'a StmtAsyncFunctionDef) -> Self {
+        Self::AsyncFunctionDefinition(value)
+    }
+}
diff --git a/crates/ruff_python_ast/src/lib.rs b/crates/ruff_python_ast/src/lib.rs
index 77bb89fa1a..552c7f02bd 100644
--- a/crates/ruff_python_ast/src/lib.rs
+++ b/crates/ruff_python_ast/src/lib.rs
@@ -2,6 +2,7 @@ pub mod all;
 pub mod call_path;
 pub mod cast;
 pub mod comparable;
+pub mod function;
 pub mod hashable;
 pub mod helpers;
 pub mod imports;