:return: a tuple of the sequence data and the last line that was read from
           the file handle/stream

def __read_seq_data(fh):
  """
  :return: a tuple of the sequence data and the last line that was read from
           the file handle/stream
  """
  line = None
  seq_data = ""
  while line is None or not _isSequenceHead(line):
    line = fh.readline()
    if line == "":
      break  # file is finished...
    if not _isSequenceHead(line):
      seq_data += line.strip()
  return seq_data, line