from cognite.client.data_classes import (
    WorkflowVersionUpsert, WorkflowDefinitionUpsert,
    WorkflowTask, FunctionTaskParameters,
)
function_task = WorkflowTask(
    external_id="my_workflow-task1",
    parameters=FunctionTaskParameters(
        external_id="my_fn_xid",
        data={"a": 1, "b": 2},
    ),
)
new_version = WorkflowVersionUpsert(
   workflow_external_id="my_workflow",
   version="1",
   workflow_definition=WorkflowDefinitionUpsert(
       tasks=[function_task],
       description="This workflow has one step",
   ),
)
res = client.workflows.versions.upsert(new_version)

{
  "items": [
    {
      "workflowExternalId": "<string>",
      "version": "<string>",
      "workflowDefinition": {
        "hash": "<string>",
        "tasks": [
          {
            "externalId": "<string>",
            "type": "function",
            "parameters": {
              "function": {
                "externalId": "my.known.id",
                "data": {
                  "key1": "value1",
                  "key2": "value2"
                }
              },
              "isAsyncComplete": false
            },
            "name": "<string>",
            "description": "<string>",
            "retries": 3,
            "timeout": 3600,
            "onFailure": "abortWorkflow",
            "dependsOn": [
              {
                "externalId": "my.known.id"
              }
            ]
          }
        ],
        "description": "<string>"
      },
      "createdTime": 1730204346000,
      "lastUpdatedTime": 1730204346000
    }
  ]
}