"    Input:  {
              choices_desc       - dict with description of choices (flat format)
              choices_order      - list of list of flat choice vectors to tune [[],[],...] - 
                                   list of list is needed to be able to enable indedepent 
                                   selection of groups of choices. For example, iterate
                                   over all possible data set sizes + random flags per data set
              choices_selection  - list of dicts with types of selection for each above group
              choices_current    - current vector of choices
              (random_module)    - if !=None, random module with seed
              (pipeline)         - if set, update it with current choices
              (custom_explore)   - enforce exploration params from command line

              (all)              - if 'yes', select all
            }

    Output: {
              return       - return code =  0, if successful
                                         >  0, if error
              (error)      - error text if return > 0

              choices_current    - list of updated choices
              choices            - dictionary of flat choices and values
              choices_order      - list of flat choices (to know order if need such as for LLVM opt)
              pipeline           - upated pipeline with choices
                                   also choices and choices_order are added to pipeline
              finish             - if True, iterations are over
            }

"