Extract the first four String elements

Return the first 4 letters of the given string.

Sample Code:

def firstFour(str):
# Enter your logic here...

Examples:

Input: 'Codetisan'
Output: 'Code'
Explanation: Elements from index 0 to 3 will be returned.

Input: '01100011'
Output: '0110'
Explanation: Elements from index 0 to 3 will be returned.