code: def restore_flattened_dict(i):
      
      # Check vars
      a={} # default
      b=i['dict']
      first=True
      for x in b:
          if first: 
             first=False
             y=x[1:2]
             if y=='@': a=[]
             else: a={}
  
          set_by_flat_key({'dict':a, 'key':x, 'value':b[x]})
  
      return {'return':0, 'dict': a}
docs: Input:  {
                dict - flattened dict
              }
  
      Output: {
                return  - return code =  0, if successful
                                      >  0, if error
                (error) - error text if return > 0
                dict    - restored dict
              }