title: Why doesn't my docopt option have its default value?
body: <p>I'm using <code>docopt</code> in an example for a module I'm working on, and all the option default values are working except one. I've modified all the code containing and surrounding the option trying to identify the problem, but it won't take a default value!</p>
  
  <p>My options block looks like this:</p>
  
  <pre><code>Options:
    --help                       Show this message and exit
    --version                    Show version info and exit
    -w WIDTH --width=WIDTH       The out to out width of the deck (feet) [default: 73]
    -g GIRDERS --girders=GIRDERS The number of girders [default: 8]
    -h HEIGHT --height=HEIGHT    The height of the girders (inches) [default: 56]
    -t THICK --thick=THICK       The deck thickness (inches) [default: 8]
    -a ADIM --adim=ADIM          The "A" dimension, max deck thick @ CL girder [default: 12]
    -l LSLP --leftslope=LSLP     The left-hand deck slope (ft/ft) [default: -0.02]
    -r RSLP --rightslope=RSLP    The right-hand deck slope (ft/ft) [default: -0.02]
    -c --center                  Indicates pivot point is at center of bridge
    -o OFFSET --offset=OFFSET    The offset of pivot point from center [default: 0]
  </code></pre>
  
  <p>The <code>girders</code> option never has a default value!</p>
  
  <p>I re-read <a href="https://stackoverflow.com/questions/13995352/why-are-defaults-not-appearing-in-my-command-line-argument-dictionary-from-docop">this question</a> several times, but it seems unrelated.</p>