lagrange_basis functions throws an error

[johnfrancmartin]

Lagrange Basis function throws an Attribute Error at the line

return (numerator * denominator.mod_inverse(o)) % o

Specifically:
AttributeError: 'int' object has no attribute 'mod_inverse'

Attempts to solve this by forcing denominator to a Bn cause further errors.

[Fronsto]

Forcing both numerator and denominator to Bn works fine.

def lagrange_basis(indexes, o, x=0):
    """ generates all lagrange basis polynomials """
    l = []
    for i in indexes:
        numerator, denominator = Bn.from_num(1), Bn.from_num(1)
        for j in indexes:
            if j != i:
                numerator = (numerator * (x - j)) % o
                denominator = (denominator * (i - j)) % o
        l.append((numerator * denominator.mod_inverse(o)) % o)
    return l