function at(time24hr, callback, pWorlds, repeat) {
  if (arguments.length === 0) {
    // TODO: Document this behaviour
    console.log(tasksToString());
    return;
  }
  var timeParts = time24hr.split(':');
  var timeMins = timeParts[0] * 60 + timeParts[1] * 1;
  if (!pWorlds || pWorlds === undefined) {
    pWorlds = utils.worlds();
  }
  if (repeat === undefined) {
    repeat = true;
  }
  utils.foreach(pWorlds, function(world) {
    atAddTask(timeMins, callback, world, repeat);
  });
}
*********************************************************************
## The at Module

The at module provides a single function `at()` which can be used to schedule
repeating (or non-repeating) tasks to be done at a particular time. 

### at() function

The utils.at() function will perform a given task at a given time in the 
(minecraft) day.

#### Parameters
time24hr : The time in 24hr form - e.g. 9:30 in the morning is '09:30' while 9:30 pm is '21:30', midnight is '00:00' and midday is '12:00'
callback : A javascript function which will be invoked at the given time.
worlds : (optional) An array of worlds. Each world has its own clock. If no array of worlds is specified, all the server's worlds are used.
repeat : (optional) true or false, default is true (repeat the task every day)

#### Example

To warn players when night is approaching:

```javascript
var utils = require('utils'),
    at = require('at');
function warning(){
  utils.players(function( player ) {
    echo( player, 'The night is dark and full of terrors!' );
  });
}
at('19:00', warning);
```
To run a task only once at the next given time:
```javascript
var utils = require('utils'),
    at = require('at');
function wakeup(){
  utils.players(function( player ) {
    echo( player, "Wake Up Folks!" );
  });
}
at('06:00', wakeup, null, false);
```
*