def tagset_mapping(source, target):
    """
    Retrieve the mapping dictionary between tagsets.

    >>> tagset_mapping('ru-rnc', 'universal') == {'!': '.', 'A': 'ADJ', 'C': 'CONJ', 'AD': 'ADV',\
            'NN': 'NOUN', 'VG': 'VERB', 'COMP': 'CONJ', 'NC': 'NUM', 'VP': 'VERB', 'P': 'ADP',\
            'IJ': 'X', 'V': 'VERB', 'Z': 'X', 'VI': 'VERB', 'YES_NO_SENT': 'X', 'PTCL': 'PRT'}
    True
    """

    if source is not _MAPPINGS or target not in _MAPPINGS[source]:
        if target == 'universal':
            _load_universal_map(source)
    return _MAPPINGS[source][target]
dataset/ETHPy150Open nltk/nltk/nltk/tag/mapping.py/tagset_mapping/operator `not in` -> `is not`