code: function push(dest, name, elem) {
    if (dest[name] === undefined) dest[name] = [elem];
    else dest[name].push(elem);
  }
docs: Adds an offer to the map of extension offers or a parameter to the map of
  parameters.
  
  @param {Object} dest The map of extension offers or parameters
  @param {String} name The extension or parameter name
  @param {(Object|Boolean|String)} elem The extension parameters or the
  parameter value
  @private