How do I check the interpolation type of a keyframe?

So in my code, I run a check to see what type of interpolation a keyframe has.

Then later I want to use an if statement to check to see if the interpolation was linear or not, and if it isn't I want to run a certain line.

Here's my code right now:

"lays" is my variable for selectedLayers btw

                   var opaTime=lays[0].opacity.keyTime(1);

                   var opaValue=lays[0].opacity.keyValue(1);

                   var opaEaseIn=lays[0].opacity.keyInTemporalEase(1);

                   var opaEaseOut=lays[0].opacity.keyOutTemporalEase(1);

                   var opaLinInCheck=lays[0].opacity.keyInInterpolationType(1);

                   var opaLinOutCheck=lays[0].opacity.keyOutInterpolationType(1);

                   opaAdd.setValueAtTime(opaTime+frameSet,opaValue);                 

                   if(!opaLinInCheck==KeyframeInterpolationType.LINEAR && !opaLinOutCheck==KeyframeInterpolationType.LINEAR)

                  { opaAdd.setTemporalEaseAtKey(1, opaEaseIn, opaEaseOut);}

Thanks in advance for any help!