def parse_string_value(str_value):
try:<EOL><INDENT>return ast.literal_eval(str_value)<EOL><DEDENT>except ValueError:<EOL><INDENT>return str_value<EOL><DEDENT>except SyntaxError:<EOL><INDENT>return str_value<EOL><DEDENT>
parse string to number if possible
    e.g. "123" => 123
         "12.2" => 12.3
         "abc" => "abc"
         "$var" => "$var"