code: def checksum_contracts(self) -> None:
          
          checksums: Dict[str, str] = {}
          for contracts_dir in self.contracts_source_dirs.values():
              file: Path
              for file in contracts_dir.glob('*.sol'):
                  checksums[file.name] = hashlib.sha256(file.read_bytes()).hexdigest()
  
          self.overall_checksum = hashlib.sha256(
              ':'.join(checksums[key] for key in sorted(checksums)).encode(),
          ).hexdigest()
          self.contracts_checksums = checksums
docs: Remember the checksum of each source, and the overall checksum.