Not Able to Solve Technical Review Error " PHP syntax error: Can't use function return value in w "

[zestmoney]

I got a technical review report and that is full of " PHP syntax error: Can't use function return value in write context " this error. 

And not able to under stand what is this error is all about. 

Can anyone let me know what is this and why this is showing for a normal function like 

[Tom Robertshaw]

Hi, I think there might be some context missing here but this error occurs when PHP code is written incorrectly. 

I normally run into this one myself when I've used the "empty" function incorrectly. It only accepts variables and so you can't make other function calls and pass the result in as an argument to it, you need to assign it to a variable first.