code: def write_stream_start(self):
      # Write BOM if needed.
      if self.encoding and self.encoding.startswith("utf-16"):
          self.stream.write("\uFEFF".encode(self.encoding))
  
imports: from .error import YAMLError
  from .events import *
label_desc: Use image node_id 47 for calling the Emitter obj's underlying member method code with example usage: obj.write_stream_start() without return types