Get values from Map : I have this Ruby map:

    PAYMENT_TYPE_TO_CURRENCY_AND_COUNTRY_MAPPING = {
        zimpler:              { 'EUR' => ['FI'], 'SEK' => ['SE']},
        qiwi:                 { 'EUR' => ['RU', 'KZ'], 'RUB' => ['RU'], 'KZT' => ['KZ'], 'USD' => ['UA']},
        payu:                 { 'CZK' => ['CZ'], 'PLN' => ['PL']},
        entercash:            { 'EUR' => ['AT', 'DE', 'FI'], 'SEK' => ['SE'] },
        davivienda:           { 'USD' => ['CO'] },
        banco_de_chile:       { 'USD' => ['CL'] }
    }

I want to get random currency and country from the structure with sample:
 

    currency       = PAYMENT_TYPE_TO_CURRENCY_TO_COUNTRY_BY_PAYMENT_TYPE_MAPPING[payment_type].keys.sample
        country         = PAYMENT_TYPE_TO_CURRENCY_TO_COUNTRY_BY_PAYMENT_TYPE_MAPPING[payment_type][currency].sample


But I get `execute': undefined method `keys'

How I can implement this?