def create_and_shift_ones(bit_string, i):
"""create bit array of value 1 and then shift it to the left i times. """
str_length = len(bit_string)
if i > (str_length - 2): # deducting 2 for the '0b' of every binary string
raise Exception('Shifting more than the length of the string')
one = BitArray('0b' + '0' * (str_length - 1) + bin(1)[2:]) # create a bitarray of ones of that length
return one.__ilshift__(i) # shift the binary representation of 1, i times.
