title: Canot instantiate boto3 S3Transfer class
body: <p>Trying to set up boto3 S3Transfer according to AWS docs:</p>
  
  <pre><code>import boto3
  client = boto3.client('s3', 'us-east-1')
  transfer = S3Transfer(client)
  </code></pre>
  
  <p>Result:</p>
  
  <pre><code>NameError: name 'S3Transfer' is not defined
  </code></pre>
  
  <p>Tried Python 2.7.11 and 3.5.1 (MacOS), same result. boto3 is installed and properly resolves in my IDE (IntelliJ):</p>
  
  <pre><code>Successfully installed boto3-1.2.3 botocore-1.3.26 docutils-0.12 futures-3.0.5 jmespath-0.9.0 python-dateutil-2.4.2
  </code></pre>
  
  <p>Any pointers would be appreciated.</p>
  
  <p>Thanks, Ron</p>