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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 get_version_from_cache_dir(src_file):
 """ Creates a version for a project out of the hash. The hash is taken from the directory of the source file. Args: src_file: The source file of the project using this function. Returns: Either returns the first 8 digits of the hash as string, the entire hash as a string if the hash consists out of less than 7 digits or None if the path is incorrect. """

    if src_file is None:
        return None

    tmp_dir = local.path(str(CFG["tmp_dir"]))
    if tmp_dir.exists():
        cache_file = tmp_dir / src_file
        dir_hash = get_hash_of_dirs(cache_file)
        if dir_hash is None:
            return None
        if len(str(dir_hash)) <= 7:
            return str(dir_hash)
        return str(dir_hash)[:7]
    return None