docstr: Verify PNG file
docstr_tok: ["Verify","PNG","file"]
code: def verify(self):
      """Verify PNG file"""
  
      if self.fp is None:
          raise RuntimeError(
              "verify must be called directly after open"
          )
  
      # back up to beginning of IDAT block
      self.fp.seek(self.tile[0][2] - 8)
  
      self.png.verify()
      self.png.close()
  
      if self._exclusive_fp:
          self.fp.close()
      self.fp = None
  
imports: import logging
  import re
  import struct
  import zlib
  from .None import Image, ImageFile, ImagePalette
  from ._binary import i8, i16be, i32be, o16be, o32be
  from ._util import py3
label_desc: Use image node_id 3 for calling the PngImageFile obj's underlying member method code with example usage: obj.verify() without return types