when extracting a prefix, it would be GREAT to be able to choose how much

[lance-sp]

at the moment, default prefix extraction is very handy,
but sometimes, i want to be able to choose how much to extract.
so if i've got an iri like <https://example.org/somedomain/something/somethingelse> i'd love to be able to choose which segments i want to extract

also, in some tools, i get auto predicates like
<https://example.org/somedomain/something/somethingelse.someColumnName>

i'd like to be able to choose

prefix somethingelse: <https://example.org/somedomain/something/somethingelse.>

somethingelse:someColumnName

[faubulous]

Good idea. I need to see if that can be done. I guess it can.