human
I wrote the below code

    T = current.T
    s3db = current.s3db
    auth = current.auth
    s3 = current.response.s3
    get_vars = current.request.get_vars
    def prep(r):
        tablename = 'project_task'
        table = s3db.project_task
        statuses = s3.project_task_active_statuses
        crud_strings = s3.crud_strings[tablename]
        if r.record:
            if r.interactive:
                project_ckeditor()
                s3.rfooter = LOAD('project', 'comments.load', args=[r.id], ajax=True)
        if (r.method == 'datalist'):
            list_fields = ['name', 'description', 'location_id', 'date_due', 'pe_id', 'status', 'modified_by']
            if current.deployment_settings.get_project_projects():
                list_fields.insert(5, (T('Project'), 'task_project.project_id'))
            s3db.configure('project_task', list_fields=list_fields)
        elif (r.method in ('create', 'create.popup')):
            project_id = r.get_vars.get('task_project.project_id', None)
            if project_id:
                s3db.project_task_project.project_id.default = project_id
        elif ('mine' in get_vars):
            query = FS('status').belongs(statuses)
            if auth.user:
                hide_fields = ('pe_id', 'status')
                if current.deployment_settings.get_project_my_tasks_include_team_tasks():
                    mtable = s3db.pr_group_membership
                    gtable = s3db.pr_group
                    gquery = ((((mtable.person_id == auth.s3_logged_in_person()) & (mtable.deleted == False)) & (gtable.id == mtable.group_id)) & (gtable.group_type == 3))
                    groups = current.db(gquery).select(gtable.pe_id)
                    pe_ids = set((group.pe_id for group in groups))
                    if pe_ids:
                        hide_fields = ('status',)
                        pe_ids.add(auth.user.pe_id)
                        query &= FS('pe_id').belongs(pe_ids)
                    else:
                        query &= (FS('pe_id') == auth.user.pe_id)
             ...

What's a good function header?
assistant
#Here's a good function header.

def project_task_controller():