def pointMutant(seq, mut):
    """
	Takes as input a sequence `seq` to mutate
	and a tuple `mut` in the form (index, 'mutated nt') ex. `(3, 'A')`.
	Returns a nucleotide sequence with a point mutation.
	"""
    return seq[:mut[0]] + mut[1] + seq[mut[0] + 1:]
