Naming a workflow task "get_task" causes "'TaskSpec' object is not callable" error

If any task in the task list is named "get_task", "has_task", or various other variations visible in https://github.com/StackStorm/orquesta/blob/b8109939b0c4ace374a42a2b5e6161a3c07b5349/orquesta/graphing.py#L78, the workflow will fail at runtime with an opaque error as seen above.

Possible resolution: use internal or hidden naming for properties of WorkflowGraph objects, or store tasks within a dictionary property of WorkflowGraph objects so that name collisions with workflow tasks can not occur or are unreasonable to accidentally discover