self.symbol_table.insert_symbol(node.name, node, None)
      return
    op_name = op_def.name
    if self.symbol_table.lookup(op_name):
      raise LookupError('Composition has not been registered for op: ' +
                        op_name)
    else:
      self.symbol_table.insert_symbol(node.name, None, None)

    self.symbol_table.enter_scope()

					if i < 0 {
						var alt Object
						if j := fieldIndex(fields, check.pkg, key.Name, true); j >= 0 {
							alt = fields[j]
						}
						msg := check.lookupError(base, key.Name, alt, true)
						check.error(kv.Key, MissingLitField, msg)
						continue
					}
					fld := fields[i]
					check.recordUse(key, fld)
					etyp := fld.typ

					if i < 0 {
						var alt Object
						if j := fieldIndex(fields, check.pkg, key.Value, true); j >= 0 {
							alt = fields[j]
						}
						msg := check.lookupError(base, key.Value, alt, true)
						check.error(kv.Key, MissingLitField, msg)
						continue
					}
					fld := fields[i]
					check.recordUse(key, fld)
					etyp := fld.typ