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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 _values(expr):
 """ Retrieve values of a dict :param expr: dict sequence / scalar :return: """

    if isinstance(expr, SequenceExpr):
        dtype = expr.data_type
    else:
        dtype = expr.value_type
    return composite_op(expr, DictValues, df_types.List(dtype.value_type))