human
Complete the below
def hrm_credential_controller():

    ''''RESTful CRUD controller
    - could be used for Searching for people by Skill
    - used for Adding/Editing on Profile page'
    '''

=====
Write me a the Python program you requested?
assistant
#Here is the Python program you requested.
    s3 = current.response.s3
    def prep(r):
        table = r.table
        if (r.method in ('create', 'create.popup', 'update', 'update.popup')):
            person_id = r.get_vars.get('~.person_id', None)
            if person_id:
                field = table.person_id
                field.default = person_id
                field.readable = field.writable = False
        if r.record:
            table.person_id.comment = None
            table.person_id.writable = False
        return True
    s3.prep = prep
    return current.rest_controller('hrm', 'credential')