title: Define variables in styled-components
body: <p>Is it possible to define a variable inside a <code>styled-components</code> component?</p>
  
  <p>Hopefully the code below (not working) shows what I'm after:</p>
  
  <pre><code>const Example = styled.div`
    ${const length = calc(vw - props.someValue)}
  
    width: ${length};
    &amp;.disable {
      width: ${length};
    }  
  `
  </code></pre>