code: func (client *Client) RemoveHostTags(host, source string) error {
  	uri := "/v1/tags/hosts/" + host
  	if source != "" {
  		uri += "?source=" + source
  	}
  	return client.doJsonRequest("DELETE", uri, nil, nil)
  }
docs: // RemoveHostTags removes all tags from a host for the given source. If none is
  // given, the API defaults to "users".