Use of Function Handle in Simulink Matlab Function

Hi,

I have the following code in my Simulink Matlab Function (found in Simulink library -> user-defined functions). This function basically performs the following: output = input x 2

function output = MultiplyFunc(input)

%#codegen

twice = @(x) x*2;

output = twice(input);

end

However, I received the coder error: This kind of expression is not supported. May I know how do I get around this problem? Any help or advice would be greatly appreciated! Thanks alot!