code: function normalize(key, expr) {
  
      if (key.slice(0, 4) !== 'incl') {
        expr = expr.replace(/[/\*]\/.*/, '').trim()
  
        // all keywords must have an expression, except `#else/#endif`
        if (!expr && key !== 'else' && key !== 'endif') {
          emitError('Expected expression for #' + key + ' in @')
          return false
        }
      }
      return expr
    }
docs: Removes any one-line comment and checks if expression is present