def save(self, fname=None):
if not fname:<EOL><INDENT>fname = self.getname()<EOL><DEDENT>assert fname != None, '<STR_LIT>'<EOL>if not fname.endswith('<STR_LIT>'):<EOL><INDENT>fname += '<STR_LIT>'<EOL><DEDENT>try:<EOL><INDENT>urlretrieve(self.url, fname)<EOL><DEDENT>except Exception:<EOL><INDENT>raise IOError('<STR_LIT>'%fname)<EOL><DEDENT>return fname<EOL>
Download the chart from the URL into a filename as a PNG

The filename defaults to the chart title (chtt) if any