`yarn start` is a command used in the context of running projects that utilize Yarn as their package manager. It's generally used in the development of JavaScript applications, most notably those built with Node.js or front-end frameworks like React. When you execute `yarch start`, Yarn looks for a `start` script defined in the project's `package.json` file and executes it. This script usually starts a development server, launches the application, or runs any task meant to kick off the development workflow. The exact action taken depends on how the `start` script is defined within the project. This command is pivotal for developers looking to test their developments in a local environment before deploying or building the production version of their application.

Mixing different grades of oil is generally not recommended but can be done if necessary, especially in a pinch. The viscosity, or thickness, of the oil affects how it lubricates your engine. When oils with different viscosities are mixed, the resulting blend could potentially not provide the optimal protection or performance expected from either grade individually. However, modern oils are designed to be compatible with each other to a certain extent. If you must mix, try to use oils of the same brand and formulation but different viscosities, and return to the recommended grade at your next oil change. Always consult your vehicle’s manual or a professional mechanic for advice specific to your situation.

Coating cake pops with nonpareils is a fun and colorful way to decorate them. First, ensure your cake pops are chilled and firm. This prevents them from crumbling when dipped. Melt candy melts or use melted chocolate as the coating; it acts as an adhesive for the nonpareils. Dip a cake pop into the melted coating until fully covered, gently tap off excess, then immediately roll it in a bowl of nonpareils or sprinkle them on top. Ensure generous coverage by pressing down lightly. Allow excess sprinkles to fall back into the bowl. Place the coated cake pop back onto the baking sheet and let set completely. Repeat with remaining cake pops. For best results, work quickly as the coating sets fast.