You need to write a function, that returns the first non-repeated character in the given string.
For example for string `"test"` function should return `'e'`.  
For string `"teeter"` function should return `'r'`.  
If a string contains all unique characters, then return just the first character of the string.  
Example: for input `"trend"` function should return `'t'`  
You can assume, that the input string has always non-zero length.
If there is no repeating character, return `null` in JS or Java, and `None` in Python.
def first_non_repeated(s):
    for character in s:
        if s.count(character) == 1:
            return character
            break
def first_non_repeated(s):
    for character in s:
        if s.count(character) == 1:
            return character
            break