code: def read(self, size=None):
          
          if self.closed:
              raise ValueError("I/O operation on closed file")
  
          buf = b""
          if self.buffer:
              if size is None:
                  buf = self.buffer
                  self.buffer = b""
              else:
                  buf = self.buffer[:size]
                  self.buffer = self.buffer[size:]
  
          if size is None:
              buf += self.fileobj.read()
          else:
              buf += self.fileobj.read(size - len(buf))
  
          self.position += len(buf)
          return buf
docs: Read at most size bytes from the file. If size is not
             present or None, read all data until EOF is reached.