Connect sftp through python script

Hi,
a requirement where to check if <VW>ER</VW> exists in xml or not.
sample xml 1:-

<?xml version="1.0" encoding="UTF-8"?>
<ORDER>
	<IDOC BEGIN="1">
		<KA1 SEGMENT="1">
			<VW>ZB</VW>
			<TN>6778</TN>
			<NR>708000</NR>
		</KA1>
		<KA1 SEGMENT="1">
			<VW>ER</VW>
			<TN>600729</TN>
			<NR>4018611</NR>
		</KA1>
	</IDOC>
</ORDER>

then I need flag = Y

sample xml 2:-

<?xml version="1.0" encoding="UTF-8"?>
<ORDER>
	<IDOC BEGIN="1">
		<KA1 SEGMENT="1">
			<VW>ZB</VW>
			<TN>6778</TN>
			<NR>708000</NR>
		</KA1>
		<KA1 SEGMENT="1">
			<VW>RE</VW>
			<TN>600729</TN>
			<NR>4018611</NR>
		</KA1>
	</IDOC>
</ORDER>

then I need flag = N