// Mouse['_listeners']


// Mouse.addListener(a)
true

// Mouse['_listeners']
[object Object]

// Mouse.addListener(a)
true

// Mouse['_listeners']
[object Object]

// Mouse.addListener(b)
true

// Mouse['_listeners']
[object Object],[object Object]

// Mouse.addListener(b)
true

// Mouse['_listeners']
[object Object],[object Object]

// Mouse.addListener(null)
true

// Mouse['_listeners']
[object Object],[object Object],null

// Mouse.addListener(1, 2)
true

// Mouse['_listeners']
[object Object],[object Object],null,1

// Mouse.removeListener(b)
true

// Mouse['_listeners']
[object Object],null,1

// Mouse.removeListener(b)
false

// Mouse['_listeners']
[object Object],null,1

// Mouse.removeListener(a)
true

// Mouse['_listeners']
null,1

// Mouse.removeListener(null)
true

// Mouse['_listeners']
1

// Mouse.removeListener(1, 2)
true

// Mouse['_listeners']


