code: def generate_extra_cases(analysis: Analysis, out: CWriter) -> None:
      out.emit("#define EXTRA_CASES \\\n")
      valid_opcodes = set(analysis.opmap.values())
      for op in range(256):
          if op not in valid_opcodes:
              out.emit(f"    case {op}: \\\n")
      out.emit("        ;\n")
  
imports: import argparse
  import os.path
  import sys
  from analyzer import Analysis, Instruction, analyze_files, Skip, Uop
  from generators_common import DEFAULT_INPUT, ROOT, write_header, cflags, StackOffset
  from cwriter import CWriter
  from typing import TextIO
  from stack import get_stack_effect
label_desc: Use image node_id 14 for calling a global function with example usage: generate_extra_cases(analysis, out) without return types