code: def configure_s3_datastore(existing_env):
      env = {}
      # Set Amazon S3 as default datastore.
      env["METAFLOW_DEFAULT_DATASTORE"] = "s3"
      # Set Amazon S3 folder for datastore.
      env["METAFLOW_DATASTORE_SYSROOT_S3"] = click.prompt(
          cyan("[METAFLOW_DATASTORE_SYSROOT_S3]")
          + " Amazon S3 folder for Metaflow artifact storage "
          + "(s3://<bucket>/<prefix>).",
          default=existing_env.get("METAFLOW_DATASTORE_SYSROOT_S3"),
          show_default=True,
      )
      # Set Amazon S3 folder for datatools.
      env["METAFLOW_DATATOOLS_S3ROOT"] = click.prompt(
          cyan("[METAFLOW_DATATOOLS_S3ROOT]")
          + yellow(" (optional)")
          + " Amazon S3 folder for Metaflow datatools "
          + "(s3://<bucket>/<prefix>).",
          default=existing_env.get(
              "METAFLOW_DATATOOLS_S3ROOT",
              os.path.join(
                  env["METAFLOW_DATASTORE_SYSROOT_S3"], "data"
              ),
          ),
          show_default=True,
      )
      return env
  
imports: import json
  import os
  import sys
  from os.path import expanduser
  from metaflow.util import to_unicode
  from metaflow._vendor import click
  from metaflow.util import to_unicode
  from .util import echo_always, makedirs
label_desc: Use image node_id 16 for calling a global function with example usage: configure_s3_datastore(existing_env) and returns: env