def __init__(self, table=None, dataset=None, project=None, query=None,
               validate=False, coder=None):

    if table is not None and query is not None:
      raise ValueError('Both a BigQuery table and a query were specified.'
                       ' Please specify only one of these.')
    elif table is None and query is None:
      raise ValueError('A BigQuery table or a query must be specified')
    elif table is not None:
      self.table_reference = _parse_table_reference(table, dataset, project)
      self.query = None
    else:
      self.query = query
      self.table_reference = None

    self.validate = validate
    self.coder = coder or RowAsDictJsonCoder()
Initialize a BigQuerySource.
dataset/ETHPy150Open GoogleCloudPlatform/DataflowPythonSDK/google/cloud/dataflow/io/bigquery.py/BigQuerySource.__init__