title: Paypal API with PHP and cURL
body: <p>I'm attempting "the first call" as outlined by the Paypal API documentation. This is the example provided that I'm following:</p>
  
  <pre><code>curl https://api.sandbox.paypal.com/v1/oauth2/token \
   -H "Accept: application/json" \
   -H "Accept-Language: en_US" \
   -u "EOJ2S-Z6OoN_le_KS1d75wsZ6y0SFdVsY9183IvxFyZp:EClusMEUk8e9ihI7ZdVLF5cZ6y0SFdVsY9183IvxFyZp" \
   -d "grant_type=client_credentials"
  </code></pre>
  
  <p>I have constructed a curl instance in PHP with all the above headers apart from the last one. What does a <code>-d</code> flag convert to as a curl option in PHP? There is little explanation there as far as I can tell. I managed to deduce <code>-u</code> as <code>CURLOPT_USERPWD</code>.</p>