title: Using the same option multiple times in Python's argparse
body: <p>I'm trying to write a script that accepts multiple input sources and does something to each one. Something like this</p>
  
  <pre><code>./my_script.py \
      -i input1_url input1_name input1_other_var \
      -i input2_url input2_name input2_other_var \
      -i input3_url input3_name
  # notice inputX_other_var is optional
  </code></pre>
  
  <p>But I can't quite figure out how to do this using <code>argparse</code>. It seems that it's set up so that each option flag can only be used once. I know how to associate multiple arguments with a single option (<code>nargs='*'</code> or <code>nargs='+'</code>), but that still won't let me use the <code>-i</code> flag multiple times. How do I go about accomplishing this?</p>
  
  <p>Just to be clear, what I would like in the end is a list of lists of strings. So</p>
  
  <pre><code>[["input1_url", "input1_name", "input1_other"],
   ["input2_url", "input2_name", "input2_other"],
   ["input3_url", "input3_name"]]
  </code></pre>