## Functions Attribute macros on functions, and on class methods, receive a `FunctionIR`: Rust ``` pub struct FunctionIR {     pub name: String,     pub span: SpanIR,     pub body_span: SpanIR,     pub signature_span: SpanIR,      // from the start to the body's opening brace     pub is_async: bool,     pub is_generator: bool,     pub is_exported: bool,     pub is_default_export: bool,     pub type_params: Vec,     pub params: Vec,     pub return_type_src: String,     pub body_src: String,     pub decorators: Vec, } pub struct FunctionParamIR {     pub name: String,     pub span: SpanIR,     pub type_src: String,     pub default_src: Option,     pub is_optional: bool,     pub is_rest: bool,     pub decorators: Vec, } ```