# Structs
DBConnectionError will be used for return case of error.
DBOperationError will be used for return case of error.
InvalidJSON will be used for return case of error.
InvalidParam will be used for return case of error.
NetworkError is error related with network operation.
NotFound will be used for return case of error.
NotSupport will be used for return case of error.
SystemError will be used for return case of error.