You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: state.rs
    path of file: ./repos/wasmtime/cranelift/interpreter/src
    
    the code of the file until where you have to start completion: //! Cranelift instructions modify the state of the machine; the [State] trait describes these
//! ways this can happen.
use crate::address::{Address, AddressSize};
use crate::frame::Frame;
use crate::interpreter::LibCallHandler;
us
    
    pub fn signature(&self) -> Signature {
        match self {
            InterpreterFunctionRef::Function(f) => f.stencil.signature.clone(),
            // CallConv here is sort of irrelevant, since we don't use it for anything
            // FIXME handle non-64bit systems
            InterpreterFunctionRef::LibCall(lc) => lc.signature(CallConv::SystemV, types::I64),
        }
    }