checks like this one and if the path exists and having that return True or False isn't a good idea. Python programming is exception-based programming meaning that hiding an exception that would be thrown (eg: an IOError due to a file not existing) is actually losing information in the API that the upstream consumer may want. It may seem counter intuitive (especially if coming from a C-programming background) but letting an exception occur and then catching it at a higher level is often preferred (and faster!) in Python eg:
```
try:
    ExrChecker("/some/path/to/nothing")
except IOError:
    print("Invalid input file")
```

That is actually faster than *always* doing a check to see if a file exists first and then opening it.