code: def __init__(self, parser, prefix):
      self.parser = parser
      self.prefix = prefix
  
imports: import argparse
  from espnet.utils.dynamic_import import dynamic_import
  from espnet.utils.fill_missing_args import fill_missing_args
label_desc: Use image node_id 1 to create a new _PrefixParser object  with example: obj = _PrefixParser(parser, prefix)