Express a function as limit plus big O and limit plus little 0

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I'm trying to express the following function in terms of a limit L plus either big O and little o. In other words,

$$ f(h) = \frac{1+h-e^h}{h^2} $$

should be expressed in the form $f(h) = L+O(h^n) = L+o(h^m)$ as $h \to 0$.

I have evaluated the limit using L'Hopital's rule, and obtain:

$$ \lim_{h \to 0} \frac{1+h-e^h}{h^2} = -\frac{1}{2} $$

However, this does not have any remaining big O or little o term. Another option I explored is to Taylor expand $f(h)$ around $h=0$, but then $O(h^n)$ will be arbitrarily chosen based on where I choose to truncate.

I read an answer to a similar problem here, but it's not clear how the answer was reached, and doesn't say anything about a little o term.

Thanks in advance!