How do I change the channel box values from MEL?

I am writing a custom script for precisely changing the rotation values using custom hotkeys.

What I want to do is, when I press some_key, I want the selected channel box attribute to increment/decrement by some value

To get the selected channel box attribute, I am using

string $selCBAttr[] = `selectedChannelBoxAttributes`;

But the problem is, it only returns a string and I don't know how to use that to make changes in the channel box.

My current code looks something like this, which I'll map to maybe Shift+Left

//print selected attribute in channelBox
string $selCBAttr[] = `selectedChannelBoxAttributes`;

print $selCBAttr;

if ('selectedChannelBoxAttributes' == "rx")
{
    rotate -r -eu -fo -1 0 0 ;
}
else if ('selectedChannelBoxAttributes' == "ry")
{
    rotate -r -eu -fo 0 -1 0 ;
}
else if ('selectedChannelBoxAttributes' == "rz")
{
    rotate -r -eu -fo 0 0 -1 ;
}

and the values will change from -1 to 1 for Shift+Right.

When I run the above code, I get the following errors:

// Warning: string $selCBAttr[] = `selectedChannelBoxAttributes`;
 // 
// Warning: Line 2.53 : Redeclaration of variable "$selCBAttr" shadows previous declaration at line 1. Previous value will be overwritten by explicit initializer. // 
// Error: if ('selectedChannelBoxAttributes' == "rx")
 // 
// Error: Line 6.5: Syntax error // 
// Error: }
 // 
// Error: Line 9.1: Syntax error // 
// Error: }
 // 
// Error: Line 13.1: Syntax error // 
// Error: }; // 
// Error: Line 17.1: Syntax error // 

So how do I so this in Maya?

# Save selected channel attributes to a string array
string $selCBAttr[] = `selectedChannelBoxAttributes`;

# Check if "rx" selected
if (stringArrayContains("rx", $selCBAttr)) {
    rotate -r -eu -fo -1 0 0 ;
}

# Check if "ry" selected
if (stringArrayContains("ry", $selCBAttr)) {
    rotate -r -eu -fo 0 -1 0 ;
}

# Check if "rz" selected
if (stringArrayContains("rz", $selCBAttr)) {
    rotate -r -eu -fo 0 0 -1 ;
}