code: public function setCurrencySymbol(string $currencySymbol): self
      {
          $conversions = [
              '€' => 'EUR',
              '$' => 'USD',
              '£' => 'GBP',
              '¥' => 'JPY'
          ];
  
          $currencySymbol = $conversions[$currencySymbol] ?? $currencySymbol;
  
          $this->currencySymbol = $currencySymbol;
  
          return $this;
      }
docs: @param string $currencySymbol
  
  @return Payment