Updating term set in SP2013

First of all, this is not something i discovered on my own, i just read it somewhere in the web and I never found the original post again, maybe because it was written in german (credits to the original author), so I decided to write this useful trick in english in order to help more people to accomplish the same task: updating a termset from code behind.
Let’s assume you need to do this from an application page, you need to use the SPSecurity and RunWithElevatedPrivileges as usual.

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SPSecurity.RunWithElevatedPrivileges(() => {  using (SPSite elevatedSite = new SPSite(site.ID, site.Zone))  {   TaxonomySession taxonomySession = new TaxonomySession(elevatedSite);   //Do here the update work  } });

Ok! This code simply doesn’t work: this is due to the fact you have to switch the context to the service account one like this.

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SPSecurity.RunWithElevatedPrivileges(() => {  using (SPSite elevatedSite = new SPSite(site.ID, site.Zone))  {   HttpContext oldContext = HttpContext.Current;     try   {    HttpContext.Current = null;    TaxonomySession taxonomySession = new TaxonomySession(elevatedSite);      //Do here the update work   }   finally   {    HttpContext.Current = oldContext;   }  } });

le jeux sont fait