code: function(params) {
  
    var baseUrl = 'http://www.omdbapi.com/';
    var query = '?';
    
    // mandatory
    query += 's='.concat(encodeURIComponent(params.query));
    
    if (params.year) {
      query += '&y='.concat(params.year);
    }
  
    if (params.type) {
      query += '&type='.concat(params.type);
    }
  
    if (params.apiKey) {
      query += '&apikey='.concat(params.apiKey);
    }
    
    return baseUrl.concat(query, '&r=json&v=1');
  }
docs: Build the url string from the parameters.
  
  @param {Object} params
  @return {String} url to call omdbapi.com
  @api private