code: func RegisterFormat(f Format) {
  	if _, ok := formatsByName[f.Name]; ok {
  		panic(fmt.Errorf("format %s is allready registered", f.Name))
  	}
  	formatsByName[f.Name] = &f
  	for _, m := range f.Ext {
  		if sf, ok := formatsByExt[m]; ok {
  			panic(fmt.Errorf("format %s is allready registered with MIME %s", sf.Name, m))
  		}
  		formatsByExt[m] = &f
  	}
  	for _, m := range f.Mime {
  		if sf, ok := formatsByMime[m]; ok {
  			panic(fmt.Errorf("format %s is allready registered with MIME %s", sf.Name, m))
  		}
  		formatsByMime[m] = &f
  	}
  }
docs: // RegisterFormat registers a new quad-file format.