How to write the following functions in python?
<p>Suppose there are only four drinks: tea, milk, coffee, and coke,</p>

<p>a list of student drinking preference is given, and I want to count how many preferences ranking eg:</p>

<pre><code> [['coke', 'milk', 'coffee', 'tea'],
      ['cola', ',milk', 'tea', 'coffee'],
      ['cola', 'milk', 'coffee', 'tea']]
</code></pre>

<p>then return :</p>

<pre><code>      {('cola', 'juice', 'coffee', 'tea'): 2,
      ('cola', 'juice', 'tea', 'coffee'): 1}
</code></pre>
