code: def cstringio_refill(self, partialread, reqlen):
      result = bytearray(partialread)
      while len(result) < reqlen:
          result += self.read(reqlen - len(result))
      self._read_buffer = BufferIO(result)
      return self._read_buffer
  
imports: import struct
  import zlib
  from thrift.compat import BufferIO, byte_index
  from thrift.protocol.TBinaryProtocol import TBinaryProtocol
  from thrift.protocol.TCompactProtocol import TCompactProtocol, readVarint, writeVarint
  from thrift.Thrift import TApplicationException
  from thrift.transport.TTransport import CReadableTransport, TMemoryBuffer, TTransportBase, TTransportException
label_desc: Use image node_id 18 for calling the THeaderTransport obj's underlying member method code with example usage: obj.cstringio_refill(partialread, reqlen) and returns: self