Function isKeyPressed

isKeyPressed(action: string): boolean
return the key press status of the specified action
Parameters
- action: string
  user defined corresponding action
Returns boolean
true if pressed
Example
```
if (me.input.isKeyPressed('left')) {
   //do something
}
else if (me.input.isKeyPressed('right')) {
   //do something else...
}
```
- Defined in packages/melonjs/src/input/keyboard.ts:116