How to concatenate many audio crossfades

[pabloriera]

Using the filter complex string for concatenating some inputs with crossfading

[0][1]acrossfade=d=0.1:c1=qsin:c2=qsin[out1];
[out1][2]acrossfade=d=0.1:c1=qsin:c2=qsin[out2];
[out2][3]acrossfade=d=0.1:c1=qsin:c2=qsin[out3];
[out3][4]acrossfade=d=0.1:c1=qsin:c2=qsin[out4]

I tried this, but couldn't workit out, it gives the error No such filter: '[input(filename'

stream = ffmpeg.input(input1)
stream1 = ffmpeg.input(input1)
for i in range(n):
    stream = stream.filter([stream, stream1], 'acrossfade', d=duration, c1='qsin',c2='qsin', o=True)
stream.output(output).run(overwrite_output=True)