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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 DataIterator(data, checklines=10, transform=None, force_dialect_check=False, from_string=False, **kwargs):
 """ Iterate over features, no matter how they are provided. Parameters data : str, iterable of Feature objs, FeatureDB `data` can be a string (filename, URL, or contents of a file, if from_string=True), any arbitrary iterable of features, or a FeatureDB (in which case its all_features() method will be called). checklines : int Number of lines to check in order to infer a dialect. transform : None or callable If not None, `transform` should accept a Feature object as its only argument and return either a (possibly modified) Feature object or a value that evaluates to False. If the return value is False, the feature will be skipped. force_dialect_check : bool If True, check the dialect of every feature. Thorough, but can be slow. from_string : bool If True, `data` should be interpreted as the contents of a file rather than the filename itself. dialect : None or dict Provide the dialect, which will override auto-detected dialects. If provided, you should probably also use `force_dialect_check=False` and `checklines=0` but this is not enforced. """


    _kwargs = dict(data=data, checklines=checklines, transform=transform,
                   force_dialect_check=force_dialect_check, **kwargs)
    if isinstance(data, six.string_types):
        if from_string:
            return _StringIterator(**_kwargs)
        else:
            if os.path.exists(data):
                return _FileIterator(**_kwargs)
            elif is_url(data):
                return _UrlIterator(**_kwargs)
    elif isinstance(data, FeatureDB):
        _kwargs['data'] = data.all_features()
        return _FeatureIterator(**_kwargs)

    else:
        return _FeatureIterator(**_kwargs)