**Is your feature request related to a problem? Please describe.** Remove the mandatory argument for the `setup` and `spam` command and make it `http://localhost:8545` by default. Add a flag `--rpc-url` to set the value. **Describe the solution you'd like** A clear and concise description of what you want to happen. **Describe alternatives you've considered** A clear and concise description of any alternative solutions or features you've considered. **Additional context** Add any other context or screenshots about the feature request here.