class_docstr: Blizzard Mipmap Format
class_docstr_tok: ["Blizzard","Mipmap","Format"]
code: def _open(self):
      self.magic = self.fp.read(4)
      self._read_blp_header()
  
      if self.magic == b"BLP1":
          decoder = "BLP1"
          self.mode = "RGB"
      elif self.magic == b"BLP2":
          decoder = "BLP2"
          self.mode = "RGBA" if self._blp_alpha_depth else "RGB"
      else:
          raise BLPFormatError(f"Bad BLP magic {repr(self.magic)}")
  
      self.tile = [(decoder, (0, 0) + self.size, 0, (self.mode, 0, 1))]
  
imports: import struct
  from io import BytesIO
  from .None import Image, ImageFile
label_desc: Use image node_id 1 for calling the BlpImageFile obj's underlying member method code with example usage: obj._open() without return types