@staticmethod
def _get_significance_code(p_value):
    """
        Significance codes:
            ‘***’ if <= 0.001
            ‘**’  if <= 0.01
            ‘*’   if <= 0.05
            ‘.’   if <= 0.1
            else ‘ ’
        :param p_value: p-value to convert
        :return: code
        """
    if p_value <= 0.001:
        return '***'
    elif p_value <= 0.01:
        return '**'
    elif p_value <= 0.05:
        return '*'
    elif p_value <= 0.1:
        return '.'
    else:
        return ''
