class RuboCop::Cop::Corrector

def self.source_buffer(source)
  source = source.processed_source if source.respond_to?(:processed_source)
  source = source.buffer if source.respond_to?(:buffer)
  source = source.source_buffer if source.respond_to?(:source_buffer)
  unless source.is_a? ::Parser::Source::Buffer
    raise TypeError, 'Expected argument to lead to a Parser::Source::Buffer ' \
                     "but got #{source.inspect}"
  end
  source
end