title: Comparing contents of lists ignoring order
body: <p>assuming I have a class shown below:</p>
  <pre class="lang-py prettyprint-override"><code>class OBJ:
      def __init__(self, a):
          self.A = a
  </code></pre>
  <p>and I have 2 lists of these objects</p>
  <pre class="lang-py prettyprint-override"><code># sorry this is a bad example, plz look at the bottom
  a = [OBJ(1), OBJ(0), OBJ(20), OBJ(-1)]
  b = [OBJ(20), OBJ(-1), OBJ(1), OBJ(0)]
  </code></pre>
  <p>how do I prove that these 2 lists' contents are the same?
  I have tried to use the sorted() method but it doesn't seem to work because you cannot logically compare 2 objects. Does anyone have a quick and efficient way of solving this? Thank you!</p>
  <p>edit:
  sorry the 2 lists are a bad example. When i mean the same i mean they are both refering to the same object. so:</p>
  <pre class="lang-py prettyprint-override"><code>a = OBJ(1)
  b = OBJ(-1)
  c = OBJ(20)
  
  x = [a,b,c]
  y = [c,a,b]
  </code></pre>
  <p>how do i prove x and y are the same?</p>