How to execute queries from a function in content migrations

[cshaa]

The documentation for content migrations says:

Functions in migration files provide a higher level of control and the ability to perform dynamic operations.

export default async function () {
  // Fetch data, execute queries, and perform other asynchronous operations here.

  // Return content migrations if needed
  return {
    queries: [
       // Individual queries
    ]
  };
};

However, it doesn't say how to execute queries from the function. I need to fetch data using a GraphQL query, perform an operation on it (compute slug columns using slugify) and only then return the mutation query that sets the slugs. How can I perform queries from the migration function?