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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def read(self, size=-1):
 """Read data from RAW file. Args: size: Number of bytes to read as integer. Actual number of bytes read is always equal to size unless EOF is reached. If size is negative or unspecified, read the entire file. Returns: data read as str. Raises: IOError: When this buffer is closed. """

    self._check_open()
    if not self._remaining():
      return ''

    data_list = []
    while True:
      remaining = self._buffer.remaining()
      if size >= 0 and size < remaining:
        data_list.append(self._buffer.read(size))
        self._offset += size
        break
      else:
        size -= remaining
        self._offset += remaining
        data_list.append(self._buffer.read())

        if self._buffer_future is None:
          if size < 0 or size >= self._remaining():
            needs = self._remaining()
          else:
            needs = size
          data_list.extend(self._get_segments(self._offset, needs))
          self._offset += needs
          break

        if self._buffer_future:
          self._buffer.reset(self._buffer_future.get_result())
          self._buffer_future = None

    if self._buffer_future is None:
      self._request_next_buffer()
    return ''.join(data_list)