I can't run lefse tutorial example

I downloaded this example: https://github.com/biobakery/biobakery/raw/master/demos/biobakery_demos/data/lefse/input/hmp_small_aerobiosis.txt

After that i run this:
format_input.py hmp_aerobiosis_small.txt hmp_aerobiosis_small.in -c 1 -s 2 -u 3 -o 1000000

and obtain this error:
Traceback (most recent call last):
File “/home/rodrigo/miniconda3/envs/lefse/bin/lefse-format_input.py”, line 459, in
feats = numerical_values(feats,params[‘norm_v’])
File “/home/rodrigo/miniconda3/envs/lefse/bin/lefse-format_input.py”, line 191, in numerical_values
feats[k] = [float(val) for val in v]
File “/home/rodrigo/miniconda3/envs/lefse/bin/lefse-format_input.py”, line 191, in
feats[k] = [float(val) for val in v]
ValueError: could not convert string to float: ‘skin’

Hi Rodrigo,
Would you mind letting me know how you set the class and subclass variables? I think that might be causing this error.
Thanks,
Meg