This project is used to build transactions for substrate chains.

PolkadotTransactionBuilder:

Its implementation of `TransactionBuilder` and implements the following methods:
1. `transfer`
2. `method_call`
3. `create_and_sign`

transfer:

Creates `PolkadotMetadataParams` for transfer call.

method_call:

Not implemented.

create_and_sign:

When `metadata` is created we use this call to create Ethereum Transaction and sign it. It takes following arguments.
`config`: chain sepecific config.
`metadata_params`: Metadata params which created metadata for this call.
`metadata`: Metadata required make transaction.
`secret_key`: wallet's secret key (used to sign the transaction).

It creates the transaction and signs it and then returns it in bytes.