[NTG-context] Can I simplify this to some sort of logic so it scales better?

[Gerben Wierda via ntg-context]

I have this:

\definemode[EN,FR,RU,PT][keep]
\doifmodeelse{EN}
  {
    \disablemode[FR]
    \disablemode[RU]
    \disablemode[PT]
  }
  {
    \doifmodeelse{FR}
    {
      \disablemode[EN]
      \disablemode[RU]
      \disablemode[PT]
    }
    {
      \doifmodeelse{RU}
      {
        \disablemode[EN]
        \disablemode[FR]
        \disablemode[PT]
      }
      {
        \doifmodeelse{PT}
        {
          \disablemode[EN]
          \disablemode[FR]
          \disablemode[RU]
        }
        {
          \enablemode[EN]
        }
      }
    }
  }

But for every language added this becomes more and more complex. I was 
wondering what would be a good approach to simplify it. 

I want to make sure that one and only one of these modes is active and that if 
no mode is entered on the command line the mode is EN.

Gerben Wierda (LinkedIn <https://www.linkedin.com/in/gerbenwierda>)
R&A IT Strategy <https://ea.rna.nl/> (main site)
Book: Chess and the Art of Enterprise Architecture <https://ea.rna.nl/the-book/>
Book: Mastering ArchiMate <https://ea.rna.nl/the-book-edition-iii/>


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