class_docstr: A base class providing the backwards-compatible spawn API for Pexpect.
  
  This should not be instantiated directly: use :class:`pexpect.spawn` or
  :class:`pexpect.fdpexpect.fdspawn`.
code: def _set_buffer(self, value):
      self._buffer = self.buffer_type()
      self._buffer.write(value)
  
imports: from io import StringIO, BytesIO
  import codecs
  import os
  import sys
  import re
  import errno
  from .exceptions import ExceptionPexpect, EOF, TIMEOUT
  from .expect import Expecter, searcher_string, searcher_re
label_desc: Use image node_id 7 for calling the SpawnBase obj's underlying member method code with example usage: obj._set_buffer(value) without return types