//
    // will be transformed to
    //
    // func.func @f(%x : bar) {
    //   ...
    // }
    // ...
    // func.call @f(%x : bar)

    CallInterfaceCallable callable = call.getCallableForCallee();
    mlir::SymbolRefAttr sym = callable.dyn_cast<mlir::SymbolRefAttr>();
    auto symbol =
        mlir::SymbolTable::lookupNearestSymbolFrom(call.getOperation(), sym);
    if (!symbol) return failure();