A simple blockchain example in Python.

snakeCoin.py

import hashlib as hasher
import datetime as date
class Block:
    def __init__(self, index, timestamp, data, previous_hash):
        self.index = index
        self.timestamp = timestamp
        self.data = data
        self.previous_hash = previous_hash
        self.hash = self.hash_block()
    def hash_block(self):
        sha = hasher.sha256()
        sha.update((str(self.index) +
                   str(self.index) +
                   str(self.timestamp) +
                   str(self.data) +
                   str(self.previous_hash)).encode("utf-8"))
        return sha.hexdigest()

def create_genesis_block():
    return Block(0, date.datetime.now(), "Genesis Block", "0")
def next_block(last_block):
    this_index = last_block.index + 1
    this_timestamp = date.datetime.now()
    this_data = "I am Block" + str(this_index)
    this_hash = last_block.hash
    return Block(this_index,
                 this_timestamp,
                 this_data,
                 this_hash)

c_block = create_genesis_block()
block_chain = [c_block]
num_of_block = 20
previous_block = block_chain[0]

for i in range(0, num_of_block):
    block_to_add = next_block(previous_block)
    block_chain.append(block_to_add)
    previous_block = block_to_add
    print("Block #%s has been added to blockchain!" % block_to_add.index)
    print("Hash: %s\n"%block_to_add.hash)