static convertUPCEtoUPCA(upce) {
			// the following line is equivalent to upce.getChars(1, 7, upceChars, 0);
			const upceChars = upce.slice(1, 7).split('').map(x => x.charCodeAt(0));
			const result = new StringBuilder( /*12*/);
			result.append(upce.charAt(0));
			let lastChar = upceChars[5];
			switch (lastChar) {
				case 0:
				case 1:
				case 2:
					result.appendChars(upceChars, 0, 2);
					result.append(lastChar);
					result.append('0000');
					result.appendChars(upceChars, 2, 3);
					break;
				case 3:
					result.appendChars(upceChars, 0, 3);
					result.append('00000');
					result.appendChars(upceChars, 3, 2);
					break;
				case 4:
					result.appendChars(upceChars, 0, 4);
					result.append('00000');
					result.append(upceChars[4]);
					break;
				default:
					result.appendChars(upceChars, 0, 5);
					result.append('0000');
					result.append(lastChar);
					break;
			}
			// Only append check digit in conversion if supplied
			if (upce.length >= 8) {
				result.append(upce.charAt(7));
			}
			return result.toString();
		}
Expands a UPC-E value back into its full, equivalent UPC-A code value.

@param upce UPC-E code as string of digits
@return equivalent UPC-A code as string of digits