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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 set_variables(self, variables, check_encoding_set, writer, unlimited_dims=None):
 """ This provides a centralized method to set the variables on the data store. Parameters variables : dict-like Dictionary of key/value (variable name / xr.Variable) pairs check_encoding_set : list-like List of variables that should be checked for invalid encoding values writer : ArrayWriter unlimited_dims : list-like List of dimension names that should be treated as unlimited dimensions. """


        for vn, v in variables.items():
            name = _encode_variable_name(vn)
            check = vn in check_encoding_set
            target, source = self.prepare_variable(
                name, v, check, unlimited_dims=unlimited_dims)

            writer.add(source, target)