code: func (r *Reference) Get(t Tag) string {
  	switch t {
  	case refNameTag:
  		return r.Name()
  	case refLengthTag:
  		return fmt.Sprint(r.lRef)
  	case assemblyIDTag:
  		return r.assemID
  	case md5Tag:
  		if r.md5 == "" {
  			return ""
  		}
  		return fmt.Sprintf("%x", []byte(r.md5))
  	case speciesTag:
  		return r.species
  	case uriTag:
  		if r.uri == nil {
  			return ""
  		}
  		return r.uri.String()
  	}
  	for _, tp := range r.otherTags {
  		if t == tp.tag {
  			return tp.value
  		}
  	}
  	return ""
  }
docs: // Get returns the string representation of the value associated with the
  // given reference line tag. If the tag is not present the empty string is returned.