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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 select_fields(self, *fields):
 """set multiple fields to be selected"""

        if fields:
            if not isinstance(fields[0], basestring): 
                fields = list(fields[0]) + list(fields)[1:]

        for field_name in fields:
            field_name = self._normalize_field_name(field_name)
            self.select_field(field_name)
        return self