code: def _updatecopy(orig, update_with, keys=None, override=False):
      
      d = orig.copy()
      if keys is None:
          keys = update_with.keys()
      for k in keys:
          if k in update_with:
              if k in d and not override:
                  continue
              d[k] = update_with[k]
      return d
docs: Update a copy of dest with source.  If `keys` is a list, then only update
      with those keys.