<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def qsturng(p, r, v):
 """Approximates the quantile p for a studentized range distribution having v degrees of freedom and r samples for probability p. Parameters p : (scalar, array_like) The cumulative probability value p >= .1 and p <=.999 (values under .5 are not recommended) r : (scalar, array_like) The number of samples r >= 2 and r <= 200 (values over 200 are permitted but not recommended) v : (scalar, array_like) The sample degrees of freedom if p >= .9: v >=1 and v >= inf else: v >=2 and v >= inf Returns ------- q : (scalar, array_like) approximation of the Studentized Range """


    if all(map(_isfloat, [p, r, v])):
        return _qsturng(p, r, v)
    return _vqsturng(p, r, v)