title: Joining lists in Python 3 like SQL JOIN
body: <p>I have 2 objects (imagine them as database tables):</p>
  
  <p>O1:<br>
  field1(id)<br>
  field2<br>
  field3  </p>
  
  <p>O2:<br>
  field1<br>
  field2<br>
  field3(id)<br>
  field4  </p>
  
  <p>I have 2 lists:<br>
  L1 is a list of O1 objects<br>
  L2 is a list of O2 objects  </p>
  
  <p><strong>Question:</strong> is there a way to join these two lists by L1.field1 and L2.field3 just like an SQL JOIN? The item count of the two lists are always equal (1:1 relation) but they are not necessarily sorted by these two fields.</p>