use namespace="System"

functions
  @{
    string BuildNumber
    {
        get 
        {
            return "t" + DateTime.UtcNow.ToString("yyMMddHHmmss");
        }
    }
    bool IsTeamCity
    {
        get
        {
            return Environment.GetEnvironmentVariable("TEAMCITY_PROJECT_NAME") != null;
        }
    }
  }