code: def pop_param(params):
      
      default = None
  
      name = params.pop(0)
      if name in (_star, _dstar):
          default = params.pop(0)
          if default == _comma:
              return name, default
  
      try:
          remainder = params.pop(0)
          if remainder == _eq:
              default = params.pop(0)
              remainder = params.pop(0)
          if remainder != _comma:
              raise ValueError(f"unexpected token: {remainder}")
  
      except IndexError:
          pass
      return name, default
docs: Pops the parameter and the "remainder" (comma, default value).
  
      Returns a tuple of ('name', default) or (_star, 'name') or (_dstar, 'name').