import xml.etree.ElementTree as ET

file_name='a.xml'
root=ET.parse(file_name).getroot()

f2 = open('b.txt','r+')

aa=''

for i in root.iter('ArchiveHeader'):
for j in i:
for k in j:
aa=aa+k.text

f2.write('\r\n')

for i in root.iter('DataGram'):
print('\r\n')
for j in i:
for k in j:
if k.text==None:
pass

        else:
            if k.tag=='PAYERBANK':
                print ('aa')
            bb=k.text
        print('|')
        aa=bb+'|'

aa=''
f2.close()

for i in root.iter('ArchiveHeader'):
for j in i:
for k in j:
aa=aa+k.text

f2.write('\r\n')

for i in root.iter('DataGram'):
#print('\r\n')
for j in i:
for k in j:
if k.text==None:
pass

        else:
            #if k.tag=='PAYERBANK':
            #    print ('aa')
            #    bb=k.text
                aa=aa+k.text
        aa=aa+'|'
f2.write(aa)
f2.write('\r\n')