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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 _dictify(field, value):
 """Make `value` suitable for a dictionary. * If `value` is an Entity, call to_dict() on it. * If value is a timestamp, turn it into a string value. * If none of the above are satisfied, return the input value """

    if value is None:
        return None
    elif field.type_:
        return value.to_dict()
    return field.dict_value(value)