Sidechains in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a sidechain name.

Blockchain / Solidity

sidechain_name = "[1]"

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Amainchain

Bblockchain

Csidechain1

Dtokenchain

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'mainchain' instead of a sidechain name

Using generic terms like 'blockchain' that don't specify sidechain

The variable sidechain_name should be set to a valid sidechain identifier, such as "sidechain1".

2fill in blank

medium

Complete the code to initialize the sidechain block height.

Blockchain / Solidity

sidechain_block_height = [1]

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A"0"

B0

CNone

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string '0' instead of integer 0

Using None or negative numbers

The block height should be an integer starting at 0 for a new sidechain.

3fill in blank

hard

Fix the error in the function that checks if a block belongs to the sidechain.

Blockchain / Solidity

def is_sidechain_block(block):
    return block.chain_id == [1]

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Asidechain_id

B"sidechain"

C"mainchain"

Dblock.chain_id

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing to a string literal instead of the sidechain ID variable

Comparing the variable to itself

The function should compare block.chain_id to the variable sidechain_id that stores the sidechain's ID.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps block hashes to their heights only for sidechain blocks.

Blockchain / Solidity

sidechain_blocks = {block.hash: block.[1] for block in blocks if block.chain_id [2] sidechain_id}

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Aheight

B!=

C==

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' instead of '==' in the condition

Using 'index' instead of 'height' for block attribute

The dictionary maps each block's hash to its height only if the block's chain_id equals the sidechain_id.

5fill in blank

hard

Fill all three blanks to create a function that returns a list of sidechain block hashes with height greater than a given value.

Blockchain / Solidity

def get_sidechain_hashes(min_height):
    return [block.[1] for block in blocks if block.chain_id == [2] and block.[3] > min_height]

Drag options to blanks, or click blank then click option'

Ahash

Bsidechain_id

Cheight

Dtimestamp

Attempts:

3 left

💡 Hint

Common Mistakes

Using timestamp instead of height for comparison

Comparing to wrong chain ID variable

The function returns hashes of blocks where the chain ID matches the sidechain and the block height is greater than min_height.