How to use the scalecodec.types.Struct function in scalecodec

def process(self):
        return self.get_next_bytes(self.element_count).decode()


class ChangesTrieRoot(Bytes):
    pass


class SealV0(Struct):
    type_string = '(u64, Signature)'

    type_mapping = (('slot', 'u64'), ('signature', 'Signature'))


class Consensus(Struct):
    type_string = '(ConsensusEngineId, Vec)'

    type_mapping = (('engine', 'ConsensusEngineId'), ('data', 'HexBytes'))


class Seal(Struct):
    type_string = '(ConsensusEngineId, Bytes)'

    type_mapping = (('engine', 'ConsensusEngineId'), ('data', 'HexBytes'))


class PreRuntime(Struct):
    type_string = '(ConsensusEngineId, Bytes)'

    type_mapping = (('engine', 'ConsensusEngineId'), ('data', 'HexBytes'))

pass


class PrefabWasmModule(Struct):
    type_string = 'wasm::PrefabWasmModule'

    type_mapping = (
        ('scheduleVersion', 'Compact'),
        ('initial', 'Compact'),
        ('maximum', 'Compact'),
        ('_reserved', 'Option'),
        ('code', 'Bytes'),
    )


class SessionKeysSubstrate(Struct):

    type_mapping = (
        ('grandpa', 'AccountId'),
        ('babe', 'AccountId'),
        ('im_online', 'AccountId'),
    )


class LegacyKeys(Struct):

    type_mapping = (
        ('grandpa', 'AccountId'),
        ('babe', 'AccountId'),
    )

# Encode call params
        if len(self.call_function.args) > 0:
            for arg in self.call_function.args:
                if arg.name not in value['call_args']:
                    raise ValueError('Parameter \'{}\' not specified'.format(arg.name))
                else:
                    param_value = value['call_args'][arg.name]

                    arg_obj = self.get_decoder_class(arg.type, metadata=self.metadata)
                    data += arg_obj.encode(param_value)

        return data


class ProposalPreimage(Struct):
    type_string = '(Vec, AccountId, BalanceOf, BlockNumber)'

    type_mapping = (
        ("proposal", "HexBytes"),
        ("registredBy", "AccountId"),
        ("deposit", "BalanceOf"),
        ("blockNumber", "BlockNumber")
    )
    def process(self):

        result = {}
        for key, data_type in self.type_mapping:
            result[key] = self.process_type(data_type, metadata=self.metadata).value

        # Replace HexBytes with actual proposal
        result['proposal'] = Proposal(ScaleBytes(result['proposal']), metadata=self.metadata).decode()

result = {}
        for key, data_type in self.type_mapping:
            result[key] = self.process_type(data_type, metadata=self.metadata).value

        # Replace HexBytes with actual proposal
        result['proposal'] = Proposal(ScaleBytes(result['proposal']), metadata=self.metadata).decode()

        return result


class Proposal(BoxProposal):
    type_string = '>::Proposal'


class ValidatorPrefs(Struct):
    type_string = '(Compact)'

    type_mapping = (('commission', 'Compact'),)


class ValidatorPrefsLegacy(Struct):
    type_string = '(Compact,Compact)'

    type_mapping = (('unstakeThreshold', 'Compact'), ('validatorPayment', 'Compact'))


class Linkage(Struct):
    type_string = 'Linkage'

    type_mapping = (
        ('previous', 'Option'),

type_mapping = (
        ('grandpa', 'AccountId'),
    )


class QueuedKeys(Struct):

    type_string = '(ValidatorId, Keys)'

    type_mapping = (
        ('validator', 'ValidatorId'),
        ('keys', 'Keys'),
    )


class LegacyQueuedKeys(Struct):

    type_string = '(ValidatorId, LegacyKeys)'

    type_mapping = (
        ('validator', 'ValidatorId'),
        ('keys', 'LegacyKeys'),
    )


class EdgewareQueuedKeys(Struct):

    type_string = '(ValidatorId, EdgewareKeys)'

    type_mapping = (
        ('validator', 'ValidatorId'),
        ('keys', 'EdgewareKeys'),

('maximum', 'Compact'),
        ('_reserved', 'Option'),
        ('code', 'Bytes'),
    )


class SessionKeysSubstrate(Struct):

    type_mapping = (
        ('grandpa', 'AccountId'),
        ('babe', 'AccountId'),
        ('im_online', 'AccountId'),
    )


class LegacyKeys(Struct):

    type_mapping = (
        ('grandpa', 'AccountId'),
        ('babe', 'AccountId'),
    )


class EdgewareKeys(Struct):
    type_mapping = (
        ('grandpa', 'AccountId'),
    )


class QueuedKeys(Struct):

    type_string = '(ValidatorId, Keys)'

result['proposal'] = Proposal(ScaleBytes(result['proposal']), metadata=self.metadata).decode()

        return result


class Proposal(BoxProposal):
    type_string = '>::Proposal'


class ValidatorPrefs(Struct):
    type_string = '(Compact)'

    type_mapping = (('commission', 'Compact'),)


class ValidatorPrefsLegacy(Struct):
    type_string = '(Compact,Compact)'

    type_mapping = (('unstakeThreshold', 'Compact'), ('validatorPayment', 'Compact'))


class Linkage(Struct):
    type_string = 'Linkage'

    type_mapping = (
        ('previous', 'Option'),
        ('next', 'Option')
    )


class GenericAccountId(H256):

class LegacyKeys(Struct):

    type_mapping = (
        ('grandpa', 'AccountId'),
        ('babe', 'AccountId'),
    )


class EdgewareKeys(Struct):
    type_mapping = (
        ('grandpa', 'AccountId'),
    )


class QueuedKeys(Struct):

    type_string = '(ValidatorId, Keys)'

    type_mapping = (
        ('validator', 'ValidatorId'),
        ('keys', 'Keys'),
    )


class LegacyQueuedKeys(Struct):

    type_string = '(ValidatorId, LegacyKeys)'

    type_mapping = (
        ('validator', 'ValidatorId'),
        ('keys', 'LegacyKeys'),

self.ss58_address = None
        super().__init__(data, sub_type, metadata)

    def process_encode(self, value):
        if value[0:2] != '0x' and len(value) == 47:
            from scalecodec.utils.ss58 import ss58_decode
            self.ss58_address = value
            value = '0x{}'.format(ss58_decode(value))
        return super().process_encode(value)


class GenericAccountIndex(U32):
    pass


class KeyValue(Struct):
    type_string = '(Vec, Vec)'
    type_mapping = (('key', 'Vec'), ('value', 'Vec'))


class NewAccountOutcome(CompactU32):
    type_string = 'NewAccountOutcome'


class Vec(ScaleType):

    def __init__(self, data=None, **kwargs):
        self.elements = []
        super().__init__(data, **kwargs)

    def process(self):
        element_count = self.process_type('Compact').value

pass


class SealV0(Struct):
    type_string = '(u64, Signature)'

    type_mapping = (('slot', 'u64'), ('signature', 'Signature'))


class Consensus(Struct):
    type_string = '(ConsensusEngineId, Vec)'

    type_mapping = (('engine', 'ConsensusEngineId'), ('data', 'HexBytes'))


class Seal(Struct):
    type_string = '(ConsensusEngineId, Bytes)'

    type_mapping = (('engine', 'ConsensusEngineId'), ('data', 'HexBytes'))


class PreRuntime(Struct):
    type_string = '(ConsensusEngineId, Bytes)'

    type_mapping = (('engine', 'ConsensusEngineId'), ('data', 'HexBytes'))


class LogDigest(Enum):

    value_list = ['Other', 'AuthoritiesChange', 'ChangesTrieRoot', 'SealV0', 'Consensus', 'Seal', 'PreRuntime']

    def __init__(self, data, **kwargs):