code: def validate_transaction_schema(tx):
      
      _validate_schema(TX_SCHEMA_COMMON, tx)
      if tx['operation'] == 'TRANSFER':
          _validate_schema(TX_SCHEMA_TRANSFER, tx)
      else:
          _validate_schema(TX_SCHEMA_CREATE, tx)
docs: Validate a transaction dict.
  
      TX_SCHEMA_COMMON contains properties that are common to all types of
      transaction. TX_SCHEMA_[TRANSFER|CREATE] add additional constraints on top.