class ActionController::Parameters

def each_pair(&block)

the same way as Hash#each_pair.
Convert all hashes in values into parameters, then yield each pair in 
def each_pair(&block)
  return to_enum(__callee__) unless block_given?
  @parameters.each_pair do |key, value|
    yield [key, convert_hashes_to_parameters(key, value)]
  end
  self
end