Hello, I'd like to use docopt for rather complicated flags.

For a package manager I'd like to provide an interface that follows the following EBNF:

flags ::= ( '--git' 'URL' ( '--branch' 'BRANCH' | '--tag' 'TAG' | '--rev' 'REV' )? | '--path' 'PATH' | 'CRATE' ( '--vers' 'VERSION' )? )+

I tried to achieve this with the following docopt pattern:

Usage:
  prog (--git=URL [--branch=BRANCH | --tag=TAG | --rev=REV] | --path=PATH | CRATE [--version=VERSION])...

Executing this with the parameters crate1 --version=foo crate2 --git url1 --tag release --git url2 --branch develop yields the following:

{"--branch": ["develop"],
 "--git": ["url1","'url2"],
 "--path": [],
 "--rev": [],
 "--tag": ["release"],
 "--version": ["foo"],
 "CRATE": ["crate1", "crate2"]}

My problem is that I want to keep the branch, tag or rev flag together with the giturl as well as the version together with crate.
Otherwise I don't know which tag belongs to which giturl and which version to which crate.

Can someone give me a heads up on this one?
Thank you in advance!