code: @Override
      public IMonomer getMonomer(String monName, String strandName) {
          Strand strand = (Strand) strands.get(strandName);
  
          if (strand != null) {
              return (Monomer) strand.getMonomer(monName);
          } else {
              return null;
          }
      }
docs: Retrieves a Monomer object by specifying its name. [You have to specify the strand to enable
  monomers with the same name in different strands. There is at least one such case: every
  strand contains a monomer called "".]
  
  @param monName  The name of the monomer to look for
  @return The Monomer object which was asked for