Is your feature request related to a problem? Please describe.
The new get_start_end method by default we returns the outer confidence positions. However, if that position
does not have a base, it returns the inner confidence position.

Describe the solution you'd like
The ask is to add a new optional parameter that allows to define the strictness of the returned positions.
The current behavior is more alike to an "auto" mode, since we might fall back to the inner confidence positions
if the outer confidence positions do not have a base. A potential "strict" mode would only return the outer confidence positions, and raise an error if the outer confidence positions do not have a base.