>This is the third part to a series of tutorials.
The goal is to produce a hands-on guide for people who want to jump straight into developing tools for STEEM.

- [part1](https://steemit.com/busy/@felixxx/python-for-steem-how-to-beem)
-  [part2](https://steemit.com/busy/@felixxx/pyhton-for-steem-2-json)
___
## API
####
Whenever I query data 'from the blockchain', I have to connect to a node that runs the corresponding API plugin to my request. I just got reminded of how little I understand about [this](https://steemit.com/testnet/@felixxx/q0et70).
I will stick to what works for me and explain as best as I can.
For this guide I will treat the API like a black box and will look at beem's modules only. Most of beem's methods closely reflect the underlying API calls, though.

## Modules
####
These are beem's modules
https://beem.readthedocs.io/en/latest/modules.html

![image.png](https://ipfs.busy.org/ipfs/QmPYo93zhr7N9BxGbNrQZscYFqWbAACoHyZvpt7ss1CRrw)


In the last part, I used the ``blockchain`` module.
https://beem.readthedocs.io/en/latest/beem.blockchain.html

```
from beem.blockchain import Blockchain
blockchain = Blockchain()
```
This instantiates ``blockchain`` as of the class Blockchain like defined in:
https://github.com/holgern/beem/blob/master/beem/blockchain.py

In the documentation you can look up, which parameters the different methods accept and what data type they will return.

```
head_block = blockchain.get_current_block_num()
```
The method ``get_current_block_num``,  returns an ``int``.

## account.py
####
As an example, I will go through some methods of the ``account`` module;
https://beem.readthedocs.io/en/latest/beem.account.html

#### method: ``balances``
####
```
from beem.account import Account

test_account = Account(account = 'holger80')
print(test_account.balances)
```

This returns a dictionary, but the print() function will print it as a string automagically.

#### method: ``get_balances()``
####
```
from beem.account import Account

test_account = Account(account = "holger80")
print(test_account.get_balances())
```
This returns the same dictionary as the ``balances`` method does.

#### method: ``get_voting_power()``
####

beem has some higher level functions, which are abstracted from the raw API data:

```
from beem.account import Account

test_account = Account(account = "holger80")
print(test_account.get_voting_power())
print(test_account.get_voting_power(with_regeneration = False))
```
By default, the parameter ``with_regeneration`` is set to ``True``.
The regeneration however, is being calculated for you by beem.
The STEEM API will always only return the voting power at the time of the last vote.

## Account.history()
####
The ``history()`` method deserves its own chapter.
Sadly, the default node set in beem does not support it at the moment.
I have to set the node by hand like this:
```
from beem import Steem
from beem.instance import set_shared_steem_instance

steemit_api = Steem(node=["https://api.steemit.com"])
set_shared_steem_instance(steemit_api)
```

This makes our black box API work again.
Leave this in front of all examples from now on, for good measure.
____
For most purposes, ``history_reverse`` is the more useful function, but is derived from ``history`` anyways - It is just the other way around starting at the latest block, going backwards.

```
from beem.account import Account
from beem.blockchain import Blockchain

blockchain = Blockchain()
head_block = blockchain.get_current_block_num()

test_account = Account("holger80")

for operation in test_account.history_reverse(start = head_block, stop = head_block - 10000, use_block_num = True):
    print(operation)
```
This returns all operations during the last 10000 blocks for the specified account.
There are more examples in the documentation.

## Congratulations
####
This should enable you to explore all of beem's modules and methods.
If you want me to explain a specific method more closely, let me know in the comments or in chat. 

## Homework
####
Can you calculate the average of your last 10 curation rewards ?