title: Is it possible define an extension operator method?
body: <p>is it possible to define an extension method that at the same time is an operator?
  I want for a fixed class add the possibility to use a known operator that actually can't be applied.
  For this particular case i want to do this:</p>
  
  <pre><code>   somestring++;  //i really know that this string contains a numeric value
  </code></pre>
  
  <p>And i don't want to spread types conversions for all the code.
  I know that i could create wrapper class over an string and define that operator but i want to know if this kind of thing is possible to avoid search-and-replace every string declaration with MySpecialString.</p>
  
  <p>Edited: as most have say string is sealed, so derivation isn't possible, so i modify "derived" to "wrapper", my mistake.</p>