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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 schema( models: Sequence[Type['main.BaseModel']], *, by_alias: bool = True, title: Optional[str] = None, description: Optional[str] = None, ref_prefix: Optional[str] = None, ) -> Dict[str, Any]: """ Process a list of models and generate a single JSON Schema with all of them defined in the ``definitions`` top-level JSON key, including their sub-models. :param models: a list of models to include in the generated JSON Schema :param by_alias: generate the schemas using the aliases defined, if any :param title: title for the generated schema that includes the definitions :param description: description for the generated schema :param ref_prefix: the JSON Pointer prefix for schema references with ``$ref``, if None, will be set to the default of ``#/definitions/``. Update it if you want the schemas to reference the definitions somewhere else, e.g. for OpenAPI use ``#/components/schemas/``. The resulting generated schemas will still be at the top-level key ``definitions``, so you can extract them from there. But all the references will have the set prefix. :return: dict with the JSON Schema with a ``definitions`` top-level key including the schema definitions for the models and sub-models passed in ``models``. """

    ref_prefix = ref_prefix or default_prefix
    flat_models = get_flat_models_from_models(models)
    model_name_map = get_model_name_map(flat_models)
    definitions = {}
    output_schema: Dict[str, Any] = {}
    if title:
        output_schema['title'] = title
    if description:
        output_schema['description'] = description
    for model in models:
        m_schema, m_definitions = model_process_schema(
            model, by_alias=by_alias, model_name_map=model_name_map, ref_prefix=ref_prefix
        )
        definitions.update(m_definitions)
        model_name = model_name_map[model]
        definitions[model_name] = m_schema
    if definitions:
        output_schema['definitions'] = definitions
    return output_schema