Look the fun part here @sircork

Disclaimer: While I can provide a foundational code structure, implementing a comprehensive blockchain capable of handling all existing currencies and transactions is a massive undertaking requiring deep expertise in cryptography, distributed systems, and blockchain technology. It involves complex algorithms, security considerations, and potential legal and regulatory implications.

Recommendations:

Leverage Existing Frameworks: Consider using established blockchain frameworks like Ethereum, Hyperledger Fabric, or Corda, which provide much of the underlying infrastructure and tools.
Consult Experts: Seek guidance from blockchain developers, cryptographers, and legal experts to ensure the code is secure, compliant, and scalable.
Iterative Development: Start with a simpler version and gradually add features and complexity as you gain experience and understanding.

Basic Python Structure (Using Ethereum as a starting point):

import json
import requests

Constants

ETHEREUM_NODE_URL = "https://mainnet.infura.io/v3/<YOUR_INFURA_PROJECT_ID>"

Functions

def get_balance(address):
"""Gets the balance of an Ethereum address."""
url = f"{ETHEREUM_NODE_URL}/eth/getBalance/{address}/latest"
response = requests.get(url)
return int(response.json(), 16) / 10**18

def send_transaction(sender_private_key, recipient_address, amount):
"""Sends an Ethereum transaction."""
nonce = get_nonce(sender_private_key)
gas_price = get_gas_price()
gas_limit = 21000
data = "" # For simple transactions, data can be empty

transaction = {
    "nonce": hex(nonce),
    "gasPrice": hex(gas_price),
    "gas": hex(gas_limit),
    "to": recipient_address,
    "value": hex(int(amount * 10**18)),
    "data": data
}

signed_transaction = sign_transaction(transaction, sender_private_key)
raw_transaction = signed_transaction.rawTransaction

url = f"{ETHEREUM_NODE_URL}/eth/sendRawTransaction"
response = requests.post(url, data=raw_transaction)
return response.json()

... (other functions for interacting with the Ethereum blockchain)

Main logic

if name == "main":
# Example usage
sender_address = "0x..."
sender_private_key = "0x..."
recipient_address = "0x..."
amount = 1.0 # 1 ETH

balance = get_balance(sender_address)
print("Balance:", balance)

if balance >= amount:
    transaction_hash = send_transaction(sender_private_key, recipient_address, amount)
    print("Transaction hash:", transaction_hash)
else:
    print("Insufficient balance.")

Note: This is a simplified example. A full-fledged blockchain would involve much more complex logic, including handling multiple currencies, consensus mechanisms, smart contracts, and security measures.

Additional Considerations:

Currency Integration: Research and implement protocols for integrating other currencies (e.g., Bitcoin, ERC-20 tokens) into your blockchain.
Consensus Mechanism: Choose a suitable consensus mechanism (e.g., Proof-of-Work, Proof-of-Stake) and implement its algorithms.
Smart Contracts: If you plan to support smart contracts, develop a virtual machine and scripting language for them.
Security: Prioritize security by using strong cryptographic algorithms, validating inputs, and protecting against vulnerabilities.
Scalability: Consider techniques like sharding or sidechains to improve performance as your blockchain grows.