# example (a) loop item by item 
def reverse_version_1(s):
    '''
    Take an input string s and return a string with the characters in s reversed
    
    Testing cases: 
    >>> reverse_version_1('albion')
    'noibla'
    
    >>> reverse_version_1('alice')
     'ecila'
    '''
    result = ''
    for char in s:
        result = char + result 
    return result

# example(b) loop over the index of the string
def reverse_version_2(s):
    '''
    Take an input string s and return a string with the characters in s reversed
    
    Testing functions in the shell: 
    >>> reverse_version_2('albion')
    'noibla'
    >>> reverse_version_2('alice')
    'ecila'
    '''
    result = ''
    for index in range(len(s) - 1, -1, -1):
        result = result + s[index]
    return result

# example of looping a list
def max_version_1(s):
    '''
    Take an input list of integeter and return the maximum number
    of the list

    Testing functions in the shell: 
    >>> max_version_1([200, -50, 250, 250, 2])
    250
    '''
    max = s[0]
    for integer in s:
        if max <= integer:
            max = integer
    return max

# example of using a built-in function max() of list
def max_version_2(s):
    '''
    Take an input list of integeter and return the maximum number
    of the list

    Testing functions in the shell: 
    >>> max_version_2([200, -50, 250, 250, 2])
    250
    '''
    return max(s)