code: protected Object extractTemporaryTypeInfoKey(final Expression expression) {
          return expression instanceof VariableExpression ? findTargetVariable((VariableExpression) expression) : expression.getText();
      }
docs: When instanceof checks are found in the code, we store temporary type information data in the {@link
  TypeCheckingContext#temporaryIfBranchTypeInformation} table. This method computes the key which must be used to store this type
  info.
  
  @param expression the expression for which to compute the key
  @return a key to be used for {@link TypeCheckingContext#temporaryIfBranchTypeInformation}