 evaluate to <a href="http://clang.llvm.org/doxygen/classclang_1_1ento_1_1UnknownVal.html">UnknownVal</a>.
  This represents a case that is outside the realm of the analyzer's reasoning 
  capabilities. <tt>SVals</tt> are value objects and their values can be viewed 
  using the <tt>.dump()</tt> method. Often they wrap persistent objects such as 
  symbols or regions.
  </p>

  <p>
  <a href="http://clang.llvm.org/doxygen/classclang_1_1ento_1_1SymExpr.html">SymExpr</a> (symbol) 
  is meant to represent abst