whole_func_string: function paymentLogoType( purchase ) {
  	if ( isPaidWithCreditCard( purchase ) ) {
  		return purchase.payment.creditCard.type;
  	}
  
  	if ( isPaidWithPayPalDirect( purchase ) ) {
  		return 'placeholder';
  	}
  
  	return purchase.payment.type || null;
  }
func_code_string: function paymentLogoType( purchase ) {
  	if ( isPaidWithCreditCard( purchase ) ) {
  		return purchase.payment.creditCard.type;
  	}
  
  	if ( isPaidWithPayPalDirect( purchase ) ) {
  		return 'placeholder';
  	}
  
  	return purchase.payment.type || null;
  }
func_documentation_string: Returns the payment logo to display based on the payment method
  
  @param {Object} purchase - the purchase with which we are concerned
  @return {string|null} the payment logo type, or null if no payment type is set.