code: func (c *Client) CreateField(field *Field) error {
  	span := c.tracer.StartSpan("Client.CreateField")
  	defer span.Finish()
  
  	data := []byte(field.options.String())
  	path := fmt.Sprintf("/index/%s/field/%s", field.index.name, field.name)
  	response, _, err := c.httpRequest("POST", path, data, nil, false)
  	if err != nil {
  		if response != nil && response.StatusCode == 409 {
  			return ErrFieldExists
  		}
  		return err
  	}
  	return nil
  }
docs: // CreateField creates a field on the server using the given Field struct.