code: def __getitem__(self, key):
      value = self.lookup(key)
      if value is None:
          raise KeyError(key)
      return value
  
imports: from itertools import chain
  from .coretypes import Unit, int8, int16, int32, int64, uint8, uint16, uint32, uint64, float16, float32, float64, complex64, complex128, bool_, Decimal, TimeDelta, Option
label_desc: Use image node_id 3 for calling the TypesetRegistry obj's underlying member method code with example usage: obj.__getitem__(key) and returns: value