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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 from_dict(cls, d):
 """ Convert a dictionary into an xarray.Dataset. Input dict can take several forms:: d = {'t': {'dims': ('t'), 'data': t}, 'a': {'dims': ('t'), 'data': x}, 'b': {'dims': ('t'), 'data': y}} d = {'coords': {'t': {'dims': 't', 'data': t, 'attrs': {'units':'s'}}}, 'attrs': {'title': 'air temperature'}, 'dims': 't', 'data_vars': {'a': {'dims': 't', 'data': x, }, 'b': {'dims': 't', 'data': y}}} where 't' is the name of the dimesion, 'a' and 'b' are names of data variables and t, x, and y are lists, numpy.arrays or pandas objects. Parameters d : dict, with a minimum structure of {'var_0': {'dims': [..], \ 'data': [..]}, \ Returns ------- obj : xarray.Dataset See also -------- Dataset.to_dict DataArray.from_dict """


        if not set(['coords', 'data_vars']).issubset(set(d)):
            variables = d.items()
        else:
            import itertools
            variables = itertools.chain(d.get('coords', {}).items(),
                                        d.get('data_vars', {}).items())
        try:
            variable_dict = OrderedDict([(k, (v['dims'],
                                              v['data'],
                                              v.get('attrs'))) for
                                         k, v in variables])
        except KeyError as e:
            raise ValueError(
                "cannot convert dict without the key "
                "'{dims_data}'".format(dims_data=str(e.args[0])))
        obj = cls(variable_dict)

        # what if coords aren't dims?
        coords = set(d.get('coords', {})) - set(d.get('dims', {}))
        obj = obj.set_coords(coords)

        obj.attrs.update(d.get('attrs', {}))

        return obj