set_country
Description:
Sets the country property to country, and 
      country_code to country_code.
Set country or country_code to null to unset the relevant property in the postal address. If a 
        country_code is provided, a country must also be provided.
Parameters:
| this | |
| country | 
           the new country for the postal address, or   | 
      
| country_code | 
           the new country code for the postal address, or   |