def get_campaign_goal(campaign, goal_identifier):
    """Returns goal from given campaign and Goal_identifier.

    Args:
        campaign (dict): The running campaign
        goal_identifier (string): Goal identifier

    Returns:
        dict: Goal corresponding to goal_identifer in respective campaign
    """

    if not campaign or not goal_identifier:
        return None
    for goal in campaign.get("goals"):
        if goal.get("identifier") == goal_identifier:
            return goal
    return None