title: Solidity undefined
body: <p>I have a question when I use solidity to compile a simple contract.
  It like that:</p>
  
  <pre><code>&gt; web3.eth.getCompilers()
  ["Solidity"]
  &gt; source = "contract test { function multiply(uint a) returns(uint d) { return a * 7; } }"
  "contract test { function multiply(uint a) returns(uint d) { return a * 7; } }"
  &gt; source
  "contract test { function multiply(uint a) returns(uint d) { return a * 7; } }"
  &gt; clientContract = eth.compile.solidity(source).test
  undefined
  </code></pre>
  
  <p>I don't know why the result is "undefined", what is wrong? I'm using it on the mac os.</p>