code: func (d *DNSProvider) getTLDs() (map[string]string, error) {
  	request, err := d.newRequestGet("namecheap.domains.getTldList")
  	if err != nil {
  		return nil, err
  	}
  
  	var gtr getTldsResponse
  	err = d.do(request, &gtr)
  	if err != nil {
  		return nil, err
  	}
  
  	if len(gtr.Errors) > 0 {
  		return nil, fmt.Errorf("%s [%d]", gtr.Errors[0].Description, gtr.Errors[0].Number)
  	}
  
  	tlds := make(map[string]string)
  	for _, t := range gtr.Result {
  		tlds[t.Name] = t.Name
  	}
  	return tlds, nil
  }
docs: // getTLDs requests the list of available TLDs.
  // https://www.namecheap.com/support/api/methods/domains/get-tld-list.aspx