old_contents: 
  // Adds `db.ping()` as an alias for `db.runCommand("ping")`
  //
  // Takes an optional argument which is included in the command object; can be used to pad out
  // the size of the ping that is sent (but not the size of the reply, which will always be small).
  
  DB.prototype.ping = function (payload) {
  	var cmd = { ping: 1 };
  	if (typeof(payload) !== "undefined") {
  		cmd.payload = payload;
  	}
  	return this.runCommand(cmd);
  };
  
  
new_contents: 
  // Adds `db.ping()` as an alias for `db.runCommand("ping")`
  //
  // Takes an optional argument which is included in the command object; can be used to pad out
  // the size of the ping that is sent (but not the size of the reply, which will always be small).
  
  DB.prototype.ping = function (payload) {
  	var cmd = { ping: 1 };
  	if (typeof(payload) !== "undefined") {
  		cmd.ping = payload;
  	}
  	return this.runCommand(cmd);
  };
  
  
subject: update db.ping(payload) for https://jira.mongodb.org/browse/SERVER-51380