Korrekte Syntax für die Funktion contract.method.send()?

Ich habe ein Problem, die web3-Dokumentation in den readthedocs zu verstehen, insbesondere hier: https://web3js.readthedocs.io/en/1.0/web3-eth-contract.html#id12

myContract.methods.myMethod([param1[, param2[, ...]]]).send(options[, callback])

Sendet eine Transaktion an den Smart Contract und führt seine Methode aus. Beachten Sie, dass dies den Smart-Contract-Status ändern kann.

Ich habe in Truffle einen Smart Contract wie diesen erstellt:

pragma solidity ^0.4.15;

contract SimpleStorage {
    bytes32 public x;

    function setX(bytes32 _x) {
        x = _x;
    }

    function getX() returns (bytes32) { //just for the sake of it...
        return x;
    }
}

Mit TestRPC funktionieren die folgenden Befehle in Truffle Console:

truffle(development)> SimpleStorage.deployed().then(function(instance){contract=instance})
truffle(development)> contract.setX('aaa')
{ tx: '0xf35b0d4a840d7049f560777e47fdabdfdafdaa339dc9b17a346a14f575ba7bf9',
  receipt:
   { transactionHash: '0xf35b0d4a840d7049f560777e47fdabdfdafdaa339dc9b17a346a14f575ba7bf9',
     transactionIndex: 0,
     blockHash: '0x82408eb303b7537b03c5f3a95ec41f38b26180cf7093e9a5f403c90bed957b5e',
     blockNumber: 5,
     gasUsed: 41842,
     cumulativeGasUsed: 41842,
     contractAddress: null,
     logs: [] },
  logs: [] }
truffle(development)> contract.getX()
{ tx: '0x58a9488bf46aa92799937cca64b6507c20c4886962a6ff1476e63369ef212241',
  receipt:
   { transactionHash: '0x58a9488bf46aa92799937cca64b6507c20c4886962a6ff1476e63369ef212241',
     transactionIndex: 0,
     blockHash: '0x3e044efc580d63154a013a3534b831ea242ae42ab7f05a95d833a848c3c416c2',
     blockNumber: 6,
     gasUsed: 21537,
     cumulativeGasUsed: 21537,
     contractAddress: null,
     logs: [] },
  logs: [] }
truffle(development)> contract.getX.call()
'0x6161610000000000000000000000000000000000000000000000000000000000'

Die folgenden Befehle funktionieren jedoch nicht, ich weiß nicht, wie ich den richtigen Aufruf tätigen soll:

truffle(development)> contract.setX.send('bbb')
TypeError: contract.setX.send is not a function
    at evalmachine.<anonymous>:1:15
    at ContextifyScript.Script.runInContext (vm.js:35:29)
    at Object.exports.runInContext (vm.js:67:17)
    at TruffleInterpreter.interpret (C:\Users\gilan\AppData\Roaming\npm\node_modules\truffle\build\cli.bundled.js:213786:17)
    at bound (domain.js:280:14)
    at REPLServer.runBound [as eval] (domain.js:293:12)
    at REPLServer.<anonymous> (repl.js:513:10)
    at emitOne (events.js:96:13)
    at REPLServer.emit (events.js:188:7)
    at REPLServer.Interface._onLine (readline.js:239:10)
truffle(development)> contract.setX('bbb').send({from:web3.eth.accounts[0]})
TypeError: contract.setX(...).send is not a function
    at evalmachine.<anonymous>:1:25
    at ContextifyScript.Script.runInContext (vm.js:35:29)
    at Object.exports.runInContext (vm.js:67:17)
    at TruffleInterpreter.interpret (C:\Users\gilan\AppData\Roaming\npm\node_modules\truffle\build\cli.bundled.js:213786:17)
    at bound (domain.js:280:14)
    at REPLServer.runBound [as eval] (domain.js:293:12)
    at REPLServer.<anonymous> (repl.js:513:10)
    at emitOne (events.js:96:13)
    at REPLServer.emit (events.js:188:7)
    at REPLServer.Interface._onLine (readline.js:239:10)

Funktioniert auch nicht für die Ereignisbehandlung

truffle(development)> contract.setX('bbb').on("transactionHash",function(hash) { console.log(hash) } )
TypeError: contract.setX(...).on is not a function
    at evalmachine.<anonymous>:1:25
    at ContextifyScript.Script.runInContext (vm.js:35:29)
    at Object.exports.runInContext (vm.js:67:17)
    at TruffleInterpreter.interpret (C:\Users\gilan\AppData\Roaming\npm\node_modules\truffle\build\cli.bundled.js:213786:17)
    at bound (domain.js:280:14)
    at REPLServer.runBound [as eval] (domain.js:293:12)
    at REPLServer.<anonymous> (repl.js:513:10)
    at emitOne (events.js:96:13)
    at REPLServer.emit (events.js:188:7)
    at REPLServer.Interface._onLine (readline.js:239:10)

Funktioniert aber gut wie versprochen

truffle(development)> contract.setX('bbb').then(console.log)
{ tx: '0xa453ec572e92d42d65b111447a8055dc7a2fcf59c18f487a001ce7352d0f4f0b',
  receipt:
   { transactionHash: '0xa453ec572e92d42d65b111447a8055dc7a2fcf59c18f487a001ce7352d0f4f0b',
     transactionIndex: 0,
     blockHash: '0xbeede1cabc7613a9d8c484017e1890dd9d08a4365013deb3481fb08ad1e4bf2d',
     blockNumber: 13,
     gasUsed: 26842,
     cumulativeGasUsed: 26842,
     contractAddress: null,
     logs: [] },
  logs: [] }
truffle(development)> contract.getX.call()
'0x6262620000000000000000000000000000000000000000000000000000000000'

Kannst du mir helfen? Danke