online_return_period:    Calculation of return period T based on risk R and design life n INPUT DATA: Risk R :     (fraction of 1)  [Allowable range: 0.01-0.75] Design life n :     (No. of years)  [Allowable range: 1-200] Display full table Inlet in urban drainage. Formula: T = 1/[1 - (1-R)1/n] Reference OUTPUT: Return period T :  0 years   Your request was processed at  08:51:02 am on October 31st, 2025   [ 251031  08:51:02 ]. Thank you for running online_return_period.   Please call again.   [180208]