io.UnsupportedOperation: not readable
"r" Opens a file for reading only. "r+" Opens a file for both reading and writing. "rb" Opens a file for reading only in binary format. "rb+" Opens a file for both reading and writing in binary format. "w" Opens a file for writing only. "a" Open for writing. The file is created if it does not exist. "a+" Open for reading and writing. The file is created if it does not exist.
