function main (userId)
    
    val1 = GetReg(1) or 0 -- if GetReg is nil, then it will be equal to 0
    TRACE("val1 " ..tostring(val1))
	val2 = GetReg("temperature")
	TRACE("val2 " ..tostring(val2))
    
	
	
	val2_filtered = (val2 or 0) -- if val2 is nil, then it will be equal to 0 too.
	TRACE("val2_filtered " ..tostring(val2_filtered))
    sum = val1 + val2_filtered
	
    TRACE(sum)
  
end