title: Python hypothesis: Ensure that input lists have same length
body: <p>I'm using hypothesis to test a function that takes two lists of equal length as input. </p>
  
  <pre><code>import hypothesis.strategies as st
  from hypothesis import assume, given
  
  
  @given(st.lists(ints, min_size=1),
         st.lists(ints, min_size=1),
         )
  def test_my_func(x, y):
      assume(len(x) == len(y))
  
      # Assertions
  </code></pre>
  
  <p>This gives me the error message:</p>
  
  <blockquote>
    <p>FailedHealthCheck: It looks like your strategy is filtering out a lot
    of data. Health check found 50 filtered examples but only 4 good ones.</p>
  </blockquote>
  
  <p>The assumption that <code>len(x) == len(y)</code> is filtering out too many inputs. So I would like to generate a random positive number and use that as the length of both <code>x</code> and <code>y</code>. Is there a way this can be done?</p>