code: def prefixed_collapsible_map(m, prefix):
      
      if m == values.unset:
          return {}
  
      def flatten_dict(d, result={}, prv_keys=[]):
          for k, v in d.items():
              if isinstance(v, dict):
                  flatten_dict(v, result, prv_keys + [k])
              else:
                  result['.'.join(prv_keys + [k])] = v
  
          return result
  
      if isinstance(m, dict):
          flattened = flatten_dict(m)
          return {'{}.{}'.format(prefix, k): v for k, v in flattened.items()}
  
      return {}
docs: Return a dict of params corresponding to those in m with the added prefix