<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_current_head_version(graph):
 """ Returns the current head version. """

    script_dir = ScriptDirectory("/", version_locations=[graph.metadata.get_path("migrations")])
    return script_dir.get_current_head()