old_contents: __all__ = [ "snopt", "npsol", "lssol", "qp", "nlp", "ocp", "socp" ]
  
new_contents: ## Import problems
  import qp, nlp, ocp, socp
  
  ## Import solvers
  import snopt, npsol, lssol
  
  ## Set hierarchy
  __all__ = [ "snopt", "npsol", "lssol", "qp", "nlp", "ocp", "socp" ]
  
subject: load all submodules automatically