'Return the union of intervals of `y` when, self is in
rectangular form, or the union of intervals of `theta`
when self is in polar form.
Examples
>>> from sympy import Interval, ComplexRegion, Union
>>> a = Interval(2, 3)
>>> b = Interval(4, 5)
>>> c = Interval(1, 7)
>>> C1 = ComplexRegion(a*b)
>>> C1.b_interval
Interval(4, 5)
>>> C2 = ComplexRegion(Union(a*b, b*c))
>>> C2.b_interval
Interval(1, 7)'

@property
def b_interval(self):

    b_interval = []
    for element in self.psets:
        b_interval.append(element.args[1])
    b_interval = Union(*b_interval)
    return b_interval
