title: How to concatenate a parameter value with a constant string in Yaml
body: <p>I have an URL defined as a parameter in <code>parameters.yml</code>. I want to create a service which is a <em>SOAP</em> client. The argument of the SOAP client is an URL for a <code>wsdl</code> file. In my case, the URL of the <code>wsdl</code> file is <code>"%parameter_url%"</code> + "?wsdl"`.</p>
  
  <p>Is there a way to concatenate the "?wsdl" to a parameter already defined in YAML?</p>