module Sprockets::ProcessorUtils

def call_processors(processors, input)

Returns a Hash with :data and other processor metadata key/values.

input - Hash of input data to pass to each processor
processors - Array of processor callables

bundle.call(uglify.call(coffee.call(input)))

Think about:
The right to left order processing mirrors standard function composition.

Public: Invoke list of processors in right to left order. 
def call_processors(processors, input)
  data = input[:data] || ""
  metadata = input[:metadata] || {}
  processors.reverse_each do |processor|
    result = processor.call(input.merge(data: data, metadata: metadata))
    case result
    when NilClass
    when Hash
      data = result.delete(:data) if result.key?(:data)
      metadata.merge!(result)
    when String
      data = result
    else
      raise TypeError, "invalid processor return type: #{result.class}"
    end
  end
  metadata.merge(data: data)
end