callback-hell.js

findSomething((error, something) => {
  if (error) {
    throw new Error(error) 
  }
  transformSomething(something, (error, transformed) => {
    if (error) {
      throw new Error(error) 
    }
    validateTransformed(transformed, (error, validated) => {
      if (error) {
        throw new Error(error) 
      }
      console.log('data is valid:', validated)
    })
  })
})