Change output type of Star::get_max to Option<T>

[ihowell]

Change output type to Option<T>

nnv-rs/src/star.rs

Lines 338 to 343 in 135fc2d

	/// TODO: Change output type to Option<T>
	pub fn get_max(&self, idx: usize) -> T {
	let neg_one: T = std::convert::From::from(-1.);
	let eqn = self.representation.get_eqn(idx) * neg_one;
	if let Some(ref poly) = self.constraints {

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This comment was generated by todo based on a TODO comment in 135fc2d in #16. cc @DrKwint.

Originally posted by @todo[bot] in #16 (comment)