Functions that predefine popular/useful methods. There should be sync and async high-level methods.

• does_account_exist
  A function to query the ledger for whether the account exists.
• get_next_valid_seq_number
  A function to query the ledger for the next available sequence number for an account.
• get_balance
  A function to query the ledger for the balance of the given account.
• get_account_root
  A function to query the ledger for the AccountRoot object associated with a given address.
• get_account_info
  A function to query the ledger for account info of a given address.
• get_latest_transaction
  A function to fetch the most recent transaction on the ledger associated with an account.
• get_account_transactions
  A function to query the ledger for a list of transactions that involved a given account. It should provide a marker argument.
• get_account_payment_transactions
  A function to query the ledger for a list of payment transactions that involved a given account.
• get_latest_validated_ledger_sequence
  A function to receive the sequence number of the latest validated ledger.
• get_latest_open_ledger_sequence
  A function to receive the sequence number of the latest open ledger.
• get_fee
  A function to query the ledger for the current transaction fee.
• get_transaction_from_hash
  A function to fetch a transaction from the ledger, using a transaction hash.
• safe_sign_and_submit_transaction
  A function to sign a transaction locally and submit it to the XRP Ledger.
• safe_sign_transaction
  A function to sign a transaction locally, without trusting external rippled nodes.
• safe_sign_and_autofill_transaction
  A function to autofill relevant fields and sign a transaction locally, without trusting external rippled nodes.
• submit_transaction
  A function to submit a transaction to the ledger.
• autofill
  A function to autofill fields in a transaction.
• send_reliable_submission
  Submits a transaction and verifies that it has been included in a validated ledger.
• generate_faucet_wallet
  A function that uses Wallet::create() and funds the newly created wallet on the Testnet.