Function Frequency of Range

//@version=2
study(title='Function Frequency of Range', overlay=false)
src = input(close)
length = input(10)

f_frequency_of_range(_src, _upper, _lower, _length)=>
    _adjusted_length = _length < 1 ? 1 : _length
    _frequency = 0
    for _i = 0 to _adjusted_length-1
        if (_src[_i] >= _lower and _src[_i] <= _upper)
            _frequency := _frequency + 1
    _return = nz(_frequency, 0)/_adjusted_length

h = highest(src, length)
l = lowest(src, length)
r = h-l
f = f_frequency_of_range(src, l+r*0.1, l, length)

plot(f)