def foo(st):
    """
    Reverse vowels in a string.
      - Get index of vowels in the a st.
      - Reverse it location
      - Print results
    :param st: Target string
    :return: None
    """
    vowels = 'aeuoi'
    st = list(st)

    st_rev_vowels = st[:]
    vowel_index = [i for i, ch in enumerate(st) if ch in vowels]

    medium = int(len(vowel_index)/2)
    rev = zip(vowel_index[:medium], reversed(vowel_index))
    for i, j in rev:
        st_rev_vowels[i], st_rev_vowels[j] = st[j], st[i]

    print(''.join(st_rev_vowels))