code: func (mr *Reader) Get(ext string) string {
  	var err error
  	// No extension
  	if len(ext) == 0 {
  		return ""
  	}
  	// Strip the leading dot
  	if ext[0] == '.' {
  		ext = ext[1:]
  	}
  	mr.mu.Lock()
  	defer mr.mu.Unlock()
  	if mr.mimetypes == nil {
  		mr.mimetypes, err = readMimetypes(mr.filename)
  		if err != nil {
  			// Using the fallback hash map
  			if mime, ok := fallback[ext]; ok {
  				return mime
  			}
  			// Unable to find the mime type for the given extension
  			return ""
  		}
  	}
  	// Use the value from the hash map
  	if mime, ok := mr.mimetypes[ext]; ok {
  		return mime
  	}
  	// Using the fallback hash map
  	if mime, ok := fallback[ext]; ok {
  		return mime
  	}
  	// Unable to find the mime type for the given extension
  	return ""
  }
docs: // Get returns the mimetype, or an empty string if no mimetype or mimetype source is found