':param conn_id: The connection ID to use when fetching connection info.
:type conn_id: string
:param delegate_to: The account to impersonate, if any.
For this to work, the service account making the request must have
domain-wide delegation enabled.
:type delegate_to: string'

def __init__(self, conn_id, delegate_to=None):

    self.conn_id = conn_id
    self.delegate_to = delegate_to
    self.extras = self.get_connection(conn_id).extra_dejson
