title: s3.Object() throws TypeError: sequence item 0: expected str instance, tuple found
body: <p>Following the boto3 documentation, I tried doing this:</p>
  
  <pre><code>session = boto3.Session(
  aws_access_key_id=KEY,
  aws_secret_access_key=SECRET_KEY
  )
  s3 = session.resource('s3')
  
  obj = s3.Object('test', 'test/myfile.csv')
  </code></pre>
  
  <p>And when I run obj.get(), I receive:</p>
  
  <blockquote>
    <p>TypeError: sequence item 0: expected str instance, tuple found</p>
  </blockquote>
  
  <p>I need to get contents of this csv file.</p>
  
  <p>It works when I try the same using client instead of session:</p>
  
  <pre><code>s3 = boto3.client('s3')
  obj = s3.get_object(Bucket='test', Key='test/myfile.csv')
  </code></pre>