class_docstr: http://boto3.readthedocs.io/en/latest/reference/services/athena.html
docstr: Start an Athena Query Execution.
docstr_tok: ["Start","an","Athena","Query","Execution","."]
code: def start_query_execution(self, **kwargs):
      """Start an Athena Query Execution."""
      if self.raise_exception:
          raise ClientError(
              {"Error": {"Code": 10}}, "InvalidRequestException"
          )
      new_query_execution = self.get_start_query_execution(**kwargs)
      new_query_id = new_query_execution["QueryExecution"][
          "QueryExecutionId"
      ]
      self.query_executions[new_query_id] = new_query_execution
  
      return {"QueryExecutionId": new_query_id}
  
imports: from datetime import datetime
  import uuid
  from io import BytesIO
  import zipfile
  import boto3
  from botocore.exceptions import ClientError
  from streamalert.shared.helpers.aws_api_client import AwsS3
label_desc: Use image node_id 3 for calling the MockAthenaClient obj's underlying member method code with example usage: obj.start_query_execution() and returns: dict