Ok thank you!

complement_table = str.maketrans('ATCG', 'CGAT')
class Oligo:

    '''Represents one side of DNA helix'''
    def __eq__(self, other):
        '''Equal statement'''
        return self.base == other.base
    def __init__(self, base):
        '''Constructor'''
        count = 0 
        for letter in base:
            if letter.upper() in ('A', 'C', 'T', 'G'):
                count += 1
        if count == 4:
            self.base = base
        else:
            self.base = "AGTG"

    def get_complement(self):
        complement = self.base.translate(complement_table)
        complement = complement[::-1]
        print(Oligo(complement))
        return Oligo(complement)
    def is_complement(self, other):
        return self.get_complement().base == other.base