class WebSocket::Frame::Data

def getbytes(start_index, count)

Extract `count` bytes starting from `start_index` and unmask it if needed. 
def getbytes(start_index, count)
  data = self[start_index, count]
  data = mask(data.bytes.to_a, @masking_key).pack('C*') if @masking_key
  data
end