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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 _ToString(x):
 """The default default formatter!."""

    # Some cross-language values for primitives.  This is tested in
    # jsontemplate_test.py.
    if x is None:
        return 'null'
    if isinstance(x, six.string_types):
        return x
    return pprint.pformat(x)