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A multi-chain project requires a complete transformation of the project, both at the level of libraries, account and wallet management, and much more. Multi-chain projects should have a Multi-Chain approach from the beginning, even if it is initially developed for a particular chain, so continuous improvement and adding new blockchains will be much simpler. The clearest example is Metamask, which allows you to connect to many strings, but at the same time, let the user decide if that possibility exists.