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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 _avro_schema(read_session):
 """Extract and parse Avro schema from a read session. Args: read_session ( \ ~google.cloud.bigquery_storage_v1beta1.types.ReadSession \ ):
 The read session associated with this read rows stream. This contains the schema, which is required to parse the data blocks. Returns: Tuple[fastavro.schema, Tuple[str]]: A parsed Avro schema, using :func:`fastavro.schema.parse_schema` and the column names for a read session. """

    json_schema = json.loads(read_session.avro_schema.schema)
    column_names = tuple((field["name"] for field in json_schema["fields"]))
    return fastavro.parse_schema(json_schema), column_names