def get_length_of_missing_array (array_of_arrays):
if len(array_of_arrays)==0:
return 0
else:
lenlist = [len(i) for i in array_of_arrays ]
print(lenlist)
rangelist=[t for t in range(min(lenlist),max(lenlist)+1)]
print(rangelist)
missing=set(rangelist)-set(lenlist)
return missing.pop()
will prompt: object of type "NoneType" has no len ()
the error line is: lenlist = [len (i) for i in array_of_arrays]
but I don"t quite understand why this sentence has this error. Please help me explain it. Thank you