public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        final Variable variable = (Variable)o;

        if (myExpression != null ? !myExpression.equals(variable.myExpression) : variable.myExpression != null) return false;
        return !(myName != null ? !myName.equals(variable.myName) : variable.myName != null);
    }
public boolean equals(Object o)