def self.cognito_user(region: MU.curRegion, credentials: nil)
        region ||= myRegion
        @@cognito_user_api[credentials] ||= {}
        @@cognito_user_api[credentials][region] ||= MU::Cloud::AWS::AmazonEndpoint.new(api: "CognitoIdentityProvider", region: region, credentials: credentials)
        @@cognito_user_api[credentials][region]