[ALUG] Python question about reading files

Are there any Python people here? How do I do the equivalent of the C below in Python :- while ( (str = read(file)) != NULL) { do something; } I can read the data OK, i.e. I have opened the file and I can successfully read from the file with the line:- tagNum = tlvFile.read(3) but I don't see how to make that part of a for/while loop that exits at the end of the file. I can't use an iterator because the file is read in variable length chunks whose length depends on context. -- Chris Green