def nist_num(nist_data):
    """Converts a NIST style data point to a point.

    Parameters
    ----------
    nist_data : str 
        A nist data point.

    Returns
    -------
    d : float or complex
        a data point.
    """
    nd = nist_data
    while ('(' in nd) or (')' in nd):
        nd_pre = nd.partition('(')
        nd_post = nd.partition(')')
        nd = nd_pre[0] + nd_post[2]

    if (nd == "---") or (nd == ""):
        nd = "0.0"

    nd = nd.replace("<i>i</i>", 'j')
    d = eval(nd)
    return d