def country_prefix(country)
      country = country.to_s.upcase
      Phonelib.phone_data[country] && \
        Phonelib.phone_data[country][Core::COUNTRY_CODE]
    end
def country_prefix(country)
      country = country.to_s.upcase
      Phonelib.phone_data[country] && \
        Phonelib.phone_data[country][Core::COUNTRY_CODE]
    end
returns country prefix for provided country or nil