> ## Documentation Index
> Fetch the complete documentation index at: https://base-a060aa97-eb-mini-app-ia-overhaul.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# ERC-721 Tokens Exercise
> Exercise - Create your own NFT!
export const Danger = ({children}) => {
return ;
};
Create a contract that adheres to the following specifications.
***
## Contract
Create a contract called `HaikuNFT`. Add the following to the contract:
* A `struct` called `Haiku` to store the `address` of the `author` and `line1`, `line2`, and `line3`
* A public array to store these `haikus`
* A public `mapping` to relate `sharedHaikus` from the `address` of the wallet shared with, to the id of the Haiku NFT shared
* A public `counter` to use as the id and to track and share the total number of Haikus minted
* If 10 Haikus have been minted, the counter should be at 11, to serve as the next id
* Do **NOT** assign an id of 0 to a haiku
* Other variables as necessary to complete the task
Add the following functions.
### Constructor
As appropriate.
### Mint Haiku
Add an `external` function called `mintHaiku` that takes in the three lines of the poem. This function should mint an NFT for the minter and save their Haiku.
Haikus must be **unique**! If any line in the Haiku has been used as any line of a previous Haiku, revert with `HaikuNotUnique()`.
You **don't** have to count syllables, but it would be neat if you did! (No promises on whether or not we counted the same as you did)
### Share Haiku
Add a `public` function called `shareHaiku` that allows the owner of a Haiku NFT to share that Haiku with the designated `address` they are sending it `_to`. Doing so should add it to that address's entry in `sharedHaikus`.
If the sender isn't the owner of the Haiku, instead revert with an error of `NotYourHaiku`. Include the id of the Haiku in the error.
Remember, everything on the blockchain is public. This sharing functionality can be expanded for features similar to allowing an app user to display the selected shared haiku on their profile.
It does nothing to prevent anyone and everyone from seeing or copy/pasting the haiku!
### Get Your Shared Haikus
Add a `public` function called `getMySharedHaikus`. When called, it should return an array containing all of the haikus shared with the caller.
If there are no haikus shared with the caller's wallet, it should revert with a custom error of `NoHaikusShared`, with no arguments.
***
The contract specification contains actions that can only be performed once by a given address. As a result, the unit tests for a passing contract will only be successful the **first** time you test.
**You may need to submit a fresh deployment to pass**
### Submit your Contract and Earn an NFT Badge! (BETA)
#### Hey, where'd my NFT go!?
[Testnets](../deployment-to-testnet/test-networks) are not permanent! Base Goerli [will soon be sunset](https://base.mirror.xyz/kkz1-KFdUwl0n23PdyBRtnFewvO48_m-fZNzPMJehM4), in favor of Base Sepolia.
As these are separate networks with separate data, your NFTs **will not** transfer over.
**Don't worry!** We've captured the addresses of all NFT owners on Base Goerli and will include them when we release the mechanism to transfer these NFTs to mainnet later this year! You can also redeploy on Sepolia and resubmit if you'd like!
{/* */}