Capitalizing family name

Given a string consisting of first and last name, return the string with both lowercase first name and uppercase last name.

Sample Code:

function nameCase(str) {
// Enter your logic here...
}

Examples:

Input: 'Tom Cat'
Output: 'tom CAT'
Explanation: 'tom' is the first name and 'CAT' is the last name.

Input: 'Jerry Mouse'
Output: 'jerry MOUSE'
Explanation: 'jerry' is the first name and 'MOUSE' is the last name.