code: def _opref_parse(encoded):
      """Parses encoded opref.
  
      Format: PKG_TYPE_AND_NAME PKG_VER MODEL_NAME OP_NAME
  
      See _opref_for_string for parsing a user-provided value.
      """
      parts = util.shlex_split(encoded)
      if len(parts) != 4:
          raise OpRefError(encoded)
      pkg_type_and_name, pkg_ver, model_name, op_name = parts
      pkg_type, pkg_name = _split_pkg_type_and_name(
          pkg_type_and_name, encoded
      )
      return OpRef(pkg_type, pkg_name, pkg_ver, model_name, op_name)
  
file_path: guildai/guild/opref.py
imports: import collections
  import logging
  import os
  import re
  from guild import util
label_desc: Use image node_id 2 for calling a global function with example usage: _opref_parse(encoded) and returns: OpRef