code: @Override
      public List<Statement> expand(Term activity) {
          List<Statement> statements = new ArrayList<Statement>();
  
          BELObject firstArgument = activity.getFunctionArguments().get(0);
          Term abundance = (Term) firstArgument; // only argument of a moleculary
                                                 // activity term is the abundance
          // Molecular activities connect to its abundance term with ACTS_IN
          // relationship
          final Object obj = new Object(activity);
          Statement statement =
                  new Statement(abundance, null, null, obj, ACTS_IN);
          attachExpansionRuleCitation(statement);
          statements.add(statement);
  
          return statements;
      }
docs: {@inheritDoc}