Modify the SQL Alchemy URL object with the user to impersonate if applicable.
        :param url: SQLAlchemy URL object
        :param impersonate_user: Bool indicating if impersonation is enabled
        :param username: Effective username

def modify_url_for_impersonation(cls, url, impersonate_user, username):
        """
        Modify the SQL Alchemy URL object with the user to impersonate if applicable.
        :param url: SQLAlchemy URL object
        :param impersonate_user: Bool indicating if impersonation is enabled
        :param username: Effective username
        """
        if impersonate_user is not None and username is not None:
            url.username = username