    def parse_transformer_context(self, transformer_context):
        """
        transformer_context can be the following:
        -   None; indicates no context is used, i.e.,
            transformer can access full context
        -   a tuple/list of two int; indicates left and right context,
            any number <0 indicates infinite context
                * e.g., (5, 6) indicates that for query at x_t, transformer can
                access [t-5, t+6] (inclusive)
                * e.g., (-1, 6) indicates that for query at x_t, transformer can
                access [0, t+6] (inclusive)
        """
        if transformer_context is None:
            return None

        if not isinstance(transformer_context, Iterable):
            raise ValueError("transformer context must be Iterable if it is not None")

        if len(transformer_context) != 2:
            raise ValueError("transformer context must have length 2")

        left_context = transformer_context[0]
        if left_context < 0:
            left_context = None

        right_context = transformer_context[1]
        if right_context < 0:
            right_context = None

        if left_context is None and right_context is None:
            return None

        return (left_context, right_context)
transformer_context can be the following:
-   None; indicates no context is used, i.e.,
transformer can access full context
-   a tuple/list of two int; indicates left and right context,
any number <0 indicates infinite context
* e.g., (5, 6) indicates that for query at x_t, transformer can
access [t-5, t+6] (inclusive)
* e.g., (-1, 6) indicates that for query at x_t, transformer can
access [0, t+6] (inclusive)
examples/speech_recognition/models/vggtransformer.py