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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def is_installable_dir(path):
 """Return True if `path` is a directory containing a setup.py file."""

    if not os.path.isdir(path):
        return False
    setup_py = os.path.join(path, "setup.py")
    if os.path.isfile(setup_py):
        return True
    return False