return a stringified and numeric for these values

def _stringify_na_values(na_values):
    """ return a stringified and numeric for these values """
    result = []
    for x in na_values:
        result.append(str(x))
        result.append(x)
        try:
            v = float(x)

            # we are like 999 here
            if v == int(v):
                v = int(v)
                result.append("{value}.0".format(value=v))
                result.append(str(v))

            result.append(v)
        except (TypeError, ValueError, OverflowError):
            pass
        try:
            result.append(int(x))
        except (TypeError, ValueError, OverflowError):
            pass
    return set(result)