def lower_tr(s):
    """Call str.lower, but convert 'I' to 'ı' instead of 'i'.
    
    This is done to adhere to the Turkish alphabet.
    """
    
    r = ""
    for i in s:
        if i == "I":
            r += "ı"
        else:
            r += i.lower()
    
    return r