Polynomial Class

TwoPolynomial.py

def superscript(num):
    superscripts = dict(zip(u"0123456789", u"⁰¹²³⁴⁵⁶⁷⁸⁹"))
    return u''.join(superscripts[c] for c in unicode(num))

def str_term(coeff, (p,q)):
    if coeff is 0:
        return ''
    if coeff is 1:
        coeff = ''
    if p is q is 0:
        return coeff
    p = '' if p is 0 else u'p'+('' if p is 1 else superscript(p))
    q = '' if q is 0 else u'q'+('' if q is 1 else superscript(q))
    pre =  u'{} {} {}'.format(coeff, p, q)
    return u' '.join(pre.split())

class TwoPolynomial(dict):
    """A polynomial in two variables"""
    
    def __repr__(self):
        return 'TwoPolynomial({})'.format(dict(self))
    
    def __unicode__(self):
        sorted_keys = sorted(dict(self), reverse= True)
        return u' + '.join(str_term(self[k],k) for k in sorted_keys)
    
    def __str__(self):
        return unicode(self).encode('utf-8')