1.`web3Provider` - `Object`: a valid web3 websockets provider.
2.`options` - `Object` (optional): Options used to initialize Phoenix
-`dbFilename` - `String` (optional): Name of the database where the information will be stored (default `'phoenix.db'`)
-`callInterval` - `Number` (optional): - Interval of time in milliseconds to query a contract/address to determine changes in state or balance (default: `undefined`. Obtains data every block).
### `init()`
Initializes Phoenix
**Returns**
`Promise` that once it's resolved, will mean that Phoenix is available to use
### `close()`
Dispose and perform the cleanup necessary to remove the internal subscriptions and interval timers created by Phoenix during its normal execution.
1.`contractObject` - `web3.eth.Contract`: An already initialized contract object pointing to an address and containing a valid ABI.
2.`eventName` - `String`: The name of the event to subscribe.
3.`options` - `Object` (optional): web3 filter options object to limit the number of events based on a block number range, or indexed filters
-`filter` - `Object` (optional): Lets you filter events by indexed parameters, e.g. `{filter: {myNumber: [12,13]}}` means all events where `"myNumber"` is `12` or `13`.
-`fromBlock` - `Number` (optional): The block number from which to get events on.
-`toBlock` - `Number` (optional): The block number to get events up to (Defaults to `"latest"`)
-`topics` - `Array` (optional): This allows you to manually set the topics for the event filter. If given the filter property and event signature, (`topic[0]`) will not be set automatically.
**Returns**
`RxJS Observable` which will stream the event `returnValues`.
Track balance changes for an address on each block mined, or depending on the `callInterval` option used during Phoenix initialization.
**Parameters**
1.`address` - `String`: The address to get the balance of.
2.`tokenAddress` - `String` (optional): If you want to track the balance for an ERC20 contract, here you can specify the token address. Otherwise, Only ETH balances will be returned.