code: public static CathDatabase getCathDatabase(String version) {
  		if (version == null) version = DEFAULT_VERSION;
  		CathDatabase cath = versions.get(version);
  		if (cath == null) {
  			CathInstallation newCath = new CathInstallation();
  			newCath.setCathVersion(version);
  			cath = newCath;
  		}
  		return cath;
  	}
docs: Returns a CATH database of the specified version.
  @param version For example, "3.5.0"