Fractions

Write a complete fraction class here. It must be named Fraction and must have the following properties:

• four basic mathematical operators defined (+, -, *, /);

• elegant conversion to string in the form '3/2';

• simplification and clean-up on construction:

  • both attribute divided by the greatest common divisor,
  • denumerator not zero (ValueError should be raised in such case),
  • sign in the numerator (i.e. denumerator is always positive),
  • both attributes must be integers (TypeError if not) — you may use Python function type or isinstance for this check;

• method decimal returning the decimal value of the fraction (the numerator divided by the denumerator).