code: func (c *Client) newRequest(endpoint string, body io.Reader, v interface{}) (*http.Request, error) {
  	if !strings.HasPrefix(endpoint, "/") {
  		endpoint = "/" + endpoint
  	}
  
  	req, err := http.NewRequest("POST", "https://"+string(c.environment)+endpoint, body)
  	if err != nil {
  		return nil, err
  	}
  
  	req.Header.Add("Content-Type", "application/json")
  	req.Header.Add("User-Agent", "Plaid Go v"+internal.Version)
  
  	// Add header for Plaid API version
  	req.Header.Add("Plaid-Version", APIVersion)
  
  	return req, nil
  }
docs: // newRequest is used by Call to generate a http.Request with appropriate headers.