Get ledger fees from the sovrin network
    Example:
    fees = await vcx_ledger_get_fees()
    :return: JSON representing fees

async def vcx_ledger_get_fees() -> str:
    """
    Get ledger fees from the sovrin network
    Example:
    fees = await vcx_ledger_get_fees()
    :return: JSON representing fees
    """
    logger = logging.getLogger(__name__)

    if not hasattr(vcx_ledger_get_fees, "cb"):
        logger.debug("vcx_ledger_get_fees: Creating callback")
        vcx_ledger_get_fees.cb = create_cb(CFUNCTYPE(None, c_uint32))

    result = await do_call('vcx_ledger_get_fees',
                           vcx_ledger_get_fees.cb)

    logger.debug("vcx_ledger_get_fees completed")
    return result