I'm new to CoffeeScript and trying to understand how to refactor this example. Since both functions share canvas and context is there a way to pull them out side the functions and share them instead of repeating myself? I'm sure it is something obvious I'm missing, but I have not been able to get it to work.

CoffeeScript File

```
@draw_rectangle = ->
  canvas = document.getElementById("main_canvas")
  context = canvas.getContext("2d")
  context.fillRect(50, 25, 150, 100)

@draw_square = ->
  canvas = document.getElementById("main_canvas")
  context = canvas.getContext("2d")
  context.fillRect(100, 50, 100, 50)

```

HTML Body:

```
<body>
  <canvas id="main_canvas"></canvas>
  <p><a onclick="draw_square()" href="#">Draw Square</a></p>
  <p><a onclick="draw_rectangle()" href="#">Draw Rectangle</a></p>
</body>

```