def decode_pure(digits_values, s):
    """Decodes the string s using the digit, value associations for each
    character.

    Parameters
    ----------
    digits_values: dict
        A dictionary containing the base-10 numbers that each hexadecimal
        number corresponds to.
    s: str
        The contents of the pdb index columns.

    Returns
    -------
    The integer in base-10 corresponding to traditional base-36.
    """
    result = 0
    n = len(digits_values)
    for c in s:
        result *= n
        result += digits_values[c]
    return result
