add led demo functionality

add led demo functionality
Please fix the coding style. 
Firstly, those operators should be separated from theirs operands with one space:
```
	=  +  -  <  >  *  /  %  |  &  ^  <=  >=  ==  !=  ?  :
```

Secondly, such expressions like this:
```
 if(row>0 && row<5) {
```
Should be written with parentheses, even if according to priority of operations it should work as expected without them:
```
  if ((row > 0) && (row < 5)) {
```
It makes the expression easier to read and understand.