code: public static StructureFiletype guessFiletype(String filename) {
  		String lower = filename.toLowerCase();
  		for(StructureFiletype type : StructureFiletype.values()) {
  			for(String ext : type.getExtensions()) {
  				if(lower.endsWith(ext.toLowerCase())) {
  					return type;
  				}
  			}
  		}
  		return StructureFiletype.UNKNOWN;
  	}
docs: Attempts to guess the type of a structure file based on the extension
  @param filename
  @return