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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 _fast_dataset( variables: 'OrderedDict[Any, Variable]', coord_variables: Mapping[Any, Variable], ) -> 'Dataset': """Create a dataset as quickly as possible. Beware: the `variables` OrderedDict is modified INPLACE. """

    from .dataset import Dataset
    variables.update(coord_variables)
    coord_names = set(coord_variables)
    return Dataset._from_vars_and_coord_names(variables, coord_names)