code: def pop(self, key, default=MISSING):
          
          try:
              val = self[key]
          except KeyError:
              if default is MISSING:
                  raise
              val = default
          else:
              del self[key]
          return val
docs: 'D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
          If key is not found, d is returned if given, otherwise KeyError is raised'