code: def process_chunk(self, lenient=False):
          
  
          type, data = self.chunk(lenient=lenient)
          method = '_process_' + type.decode('ascii')
          m = getattr(self, method, None)
          if m:
              m(data)
docs: Process the next chunk and its data.
          This only processes the following chunk types:
          ``IHDR``, ``PLTE``, ``bKGD``, ``tRNS``, ``gAMA``, ``sBIT``, ``pHYs``.
          All other chunk types are ignored.
  
          If the optional `lenient` argument evaluates to `True`,
          checksum failures will raise warnings rather than exceptions.