A Python class that only prints unique files. Useful for debugging inner loops.

print_unique.py

class PrintUnique(object):
    """
    A class that keeps track of what it has printed to stdout and won't
    print anything twice.
    """
    printed = set()

    @classmethod
    def write(cls, s):
        """
        Prints a string if it hasn't been printed before.
        """
        if s not in cls.printed:
            cls.printed.add(s)
            print s

    @classmethod
    def reset(cls):
        cls.printed = set()