To open a file, use the built-in open function, with the external filename and a processing mode.
The call returns a file object, which has methods for data transfer:
afile = open(filename , mode) afile.method()
filename may include a platform-specific and absolute or relative directory path prefix.
Without a directory path, the file is assumed to exist in the current working directory, i.e., where the script runs.
The filename may contain non-ASCII Unicode characters.
The processing mode is typically the string:
|'r'||open for text input (default)|
|'w'||create and open for text output|
|'a'||open for appending text to the end.|
Adding 'b' to the mode string for binary data.
Adding '+' opens the file for both input and output.