import sys, os, errno


def atoi(v):
    try:
        return int(v or 0)
    except ValueError:
        return 0


def unlink(f):
    """Delete a file at path 'f' if it currently exists.

    Unlike os.unlink(), does not throw an exception if the file didn't already
    exist.
    """
    try:
        os.unlink(f)
    except OSError, e:
        if e.errno == errno.ENOENT:
            pass  # it doesn't exist, that's what you asked for


def mkdirp(d, mode=None):
    """Recursively create directories on path 'd'.

    Unlike os.makedirs(), it doesn't raise an exception if the last element of
    the path already exists.
    """
    try:
        if mode:
            os.makedirs(d, mode)
        else:
            os.makedirs(d)
    except OSError, e:
        if e.errno == errno.EEXIST:
            pass
        else:
            raise