The createGrimeNFT()
function uses two require
statements.
- Require Statement: must mint to the zero address.
- Require Statement: the tokenURI must not already exist.
The _uriExists
mapping to tokenURI
is set to true at the end of the createGrimeNFT()
function.
This along with the second require
statement at the start of the function, is used to keep a user from minting an NFT with the same tokenURI
twice.