code: public Variable find(String name) {
          if (context.containsKey(name)) {
              return context.get(name);
          }
          if (parent != null) {
              return parent.find(name);
          }
          return null;
      }
docs: Searches for a {@link Variable} with the given name.
  <p>
  If the variable does not exist <tt>null</tt>  will be returned
  
  @param name the name of the variable to search
  @return the variable with the given name or <tt>null</tt> if no such variable was found