Simplifies Expectation, Variance and Covariance in symbolic_probability
Simplifies Expectation, Variance and Covariance in symbolic_probability

The methods, _eval_rewrite_as_Integral and _eval_rewrite_as_Sum in
Expectation, Variance and Covariance are now decoupled, by using
same return statement.

kaushik94/sympy,kaushik94/sympy,kaushik94/sympy