Find the derivative of `x` at `x = 1`.

Explanation

f(x) = 1
`f^(.)(1)= lim_(h rarr 0) (f(1+h)-f(1))/h = lim_(h rarr 0)(1+h-1)/h = lim_(h rarr 0) h/h = lim_(h rarr0) 1 = 1`