Write a Python function named "reverse_string" that takes a string as input and returns the reverse of the input string.

Sure! Here's a Python function named "reverse_string" that takes a string as input and returns the reverse of the input string:

def reverse_string(input_str):
    return input_str[::-1]

Here, we're using Python's string slicing notation to reverse the input string. The `[::-1]` slice means to take the entire string, but step backwards by 1 character at a time. This effectively reverses the order of the string.