# File lib/aws/core/signers/version_4/chunk_signed_stream.rb, line 48
          def initialize stream, stream_size, key, key_path, datetime, signature
            @stream = stream || StringIO.new('')
            @size = self.class.signed_size(stream_size)
            @key = key
            @key_path = key_path
            @datetime = datetime
            @prev_chunk_signature = signature
            reset
          end