code: func SetTransportDefaults(t *http.Transport) *http.Transport {
  	if t.Proxy == nil {
  		t.Proxy = defaultTransport.Proxy
  	}
  	if t.Dial == nil {
  		t.Dial = defaultTransport.Dial
  	}
  	if t.TLSHandshakeTimeout == 0 {
  		t.TLSHandshakeTimeout = defaultTransport.TLSHandshakeTimeout
  	}
  	return t
  }
docs: // SetTransportDefaults applies the defaults from http.DefaultTransport
  // for the Proxy, Dial, and TLSHandshakeTimeout fields if unset