def getincrementaldecoder(encoding):
 decoder = lookup(encoding).incrementaldecoder
 if (decoder is None):
  raise LookupError(encoding)
 return decoder

def getincrementaldecoder ( encoding ) : decoder = lookup ( encoding ) . incrementaldecoder if ( decoder is None ) : raise LookupError ( encoding ) return decoder
lookup up the codec for the given encoding and return its incrementaldecoder class or factory function .