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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 special_format_field(self, obj, format_spec):
 """Know about any special formats"""

        if format_spec == "env":
            return "${{{0}}}".format(obj)
        elif format_spec == "from_env":
            if obj not in os.environ:
                raise NoSuchEnvironmentVariable(wanted=obj)
            return os.environ[obj]