def get_file_size(filename):
if filename is None:<EOL><INDENT>return float(<NUM_LIT:0>)<EOL><DEDENT>if type(filename) is list:<EOL><INDENT>return float(sum([get_file_size(x) for x in filename]))<EOL><DEDENT>try:<EOL><INDENT>total_bytes = sum([float(os.stat(f).st_size)<EOL>for f in filename.split("<STR_LIT:U+0020>") if f is not '<STR_LIT>'])<EOL><DEDENT>except OSError:<EOL><INDENT>return <NUM_LIT:0.0><EOL><DEDENT>else:<EOL><INDENT>return float(total_bytes) / (<NUM_LIT> ** <NUM_LIT:3>)<EOL><DEDENT>
Get size of all files in gigabytes (Gb).

:param str | collections.Iterable[str] filename: A space-separated
    string or list of space-separated strings of absolute file paths.
:return float: size of file(s), in gigabytes.