Making my character lose sanity when hit.

[Sneaky Axolxtl]

I am making a player mod for my friends. This character gets really upset when hurt so I wanted to make him lose sanity when hurt like Walter.
I looked into Walter's code and tried copying some of the code into my player.lua, but it didn't work. 
Little help? (Note: I have no coding experience AND I'm really dumb so this might be the wrong code.)
 

local function OnHealthDelta(inst, data)

    if data.amount < 0 then

        inst.components.sanity:DoDelta(data.amount * ((data ~= nil and data.overtime) and TUNING.WALTER_SANITY_DAMAGE_OVERTIME_RATE or TUNING.WALTER_SANITY_DAMAGE_RATE) * inst._sanity_damage_protection:Get())

    end

end

[Sneaky Axolxtl]

I figured it out!