eates two arrays, one with the possible last two digits and one with</span>
<span class="sd">    thei respective probabilities</span>

<span class="sd">    Args:</span>
<span class="sd">        num: returns numeric (ints) values. Defaluts to False,</span>
<span class="sd">            which returns strings.</span>

<span class="sd">    Returns:</span>
<span class="sd">        exp (np.array): Array with the (constant) probabilities of occurrence of</span>
<span class="sd">            each pair of last two dig