docs: def open_source_package(dr=None):
      """Like open_package(), but always open the source package"""
      if dr is None:
          dr = getcwd()
  
      for i, e in enumerate(walk_up(dr)):
  
          intr = set([DEFAULT_METATAB_FILE, LINES_METATAB_FILE, IPYNB_METATAB_FILE]) & set(e[2])
  
          if intr:
  
              return op(join(e[0], list(intr)[0] ))
  
          if i > 2:
              break
  
      return None