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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 yaml_read_irred_perts(filename, doc_tag="!IrredPerts"):
 """Read the list of irreducible perturbations from file."""

    with YamlTokenizer(filename) as r:
        doc = r.next_doc_with_tag(doc_tag)
        d = yaml.safe_load(doc.text_notag)

        return [AttrDict(**pert) for pert in d["irred_perts"]]