FirstIndexOf returns the first index of the slice for which the predicate returns true, or an empty index if no element satisfies the predicate.

MustGet returns the value of the Index if it is Some, or panics if it is None.

None creates an Index with no value.

Some creates an Index with the given value.

MaxUint is the maximum value of a uint.

ErrMissingValue occurs when a value is not present.

Index is a type alias for uint.

Predicate is a function that returns true if the element is valid.