docs: function _param(req, param, pdefault){
  
      var ret = null;
  
      // Try the route parameter space.
      if( req && req.params && typeof(req.params[param]) !== 'undefined' ){
  	ret = req.params[param];
      }
  
      // Try the get space.
      if( ! ret ){
  
  	if( req && req.query && req.query[param] && typeof(req.query[param]) !== 'undefined' ){
  	    ret = req.query[param];
  	}
      }
  
      // Otherwise, try the body space.
      if( ! ret ){
  
  	var decoded_body = req.body || {};
  	if( decoded_body && ! us.isEmpty(decoded_body) && decoded_body[param] ){
  	    ret = decoded_body[param];
  	}
      }
  
      // Reduce to first if array.
      if( us.isArray(ret) ){
  	if( ret.length === 0 ){
  	    ret = pdefault;
  	}else{
  	    ret = ret[0];
  	}
      }
  
      // Finally, default.
      if( ! ret ){
  	ret = pdefault;
      }
  
      return ret;
  }