This accessor is used to resolve a named entrypoint from an entrypoint list.
If the name is unique then module and version are not necessary. If they
are necessary but not supplied then an indeterminate entrypoint will be chosen.
The ep: scheme may be used to specify entrypoints within DPML.
module and version arguments are optional
and may be omitted if uniqueness is certain. The choosen result will
unpredicatable othewise.
See the ext_entrypoint guide for more
details on entrypoints.