A sample class is added just to check how to add any functionality in
llvm.

linkedlist to support different type of values(llvm). But there is some
issue in the push_back function declaration. After doing changes, llvm
is being built successfully but while using this in a pass an error is
being thrown when trying to run the pass. Pass is being built
successfully but while loading the pass using opt and running it with a
program symbol lookup error is being thrown.

compiler to use a template, it must see both the template definition
(not just a declaration) and the template type used to instantiate the
template.

refer https://www.learncpp.com/cpp-tutorial/133-template-classes/ (last
section)

Look at the ways to work around.