Map object has no len() in Python 3
In Python 3, map returns an iterator. If your function expects a list, the iterator has to be explicitly converted, like this:
data = list(map(...))And we can do it simply, like this
with open(args[0], "rb") as input_file: data = list(input_file.read())rb refers to read in binary mode. So, it actually returns the bytes. So, we just have to convert them to a list.
Quoting from the open's docs,
Python distinguishes between binary and text I/O. Files opened in binary mode (including 'b' in the mode argument) return contents as bytes objects without any decoding.