Manejo de archivos en Python Append Byte
file = open('myfile.dat', 'wb')
file.write('This is a sample')
file.close()
file = open('myfile.dat', 'ab')
file.seek(5)
file.write(' text')
file.close()
file = open('myfile.dat', 'rb')
print file.read() # -> This is a sample text
Defeated Dragonfly