Python

According to reverse-a-string-in-python, the solution would be

'hello world'[::-1]

To make it more readable, I have to define a function:

def reverse(target_string):
    return target_string[::-1]

Java

According to reverse-a-string-in-java, the solution would be

new StringBuilder('hello world').reverse().toString()

I think for Python, there should be a method called reverse() to let me use it like 'hello world'.reverse().