def markInputline( self, markerString = "<STR_LIT>" ):
line_str = self.line<EOL>line_column = self.column - <NUM_LIT:1><EOL>if markerString:<EOL><INDENT>line_str = "<STR_LIT>".join((line_str[:line_column],<EOL>markerString, line_str[line_column:]))<EOL><DEDENT>return line_str.strip()<EOL>
Extracts the exception line from the input string, and marks
           the location of the exception with a special symbol.