code: public boolean hasMonomer(String polymerType, String alternateId) {
      return ((monomerDB.get(polymerType) != null) && getMonomer(polymerType, alternateId) != null);
    }
docs: Checks if a specific monomer exists in the store
  
  @param polymerType polymer type of monomer
  @param alternateId alternateId of monomer
  @return true if monomer exists, false if not