Question: I have this array of tuplets containing strings and a url

```
var notifications:[(body: String, header: String, icon: URL)] = []

```

Now, I want to append a tuplet with an empty URL

I tried

```
notifications.append((body: "some text, header: "some more text", icon: nil))

```

but that is not allowed

What is the way to do this?

Answer: 
There's a difference between `str.replace` and `pd.Series.str.replace`. The former accepts substring replacements, and the latter accepts regex patterns.

Using `str.replace`, you'd need to pass a *raw string* instead.

```
df['col'] = df['col'].str.replace(r'\\d', '_dbl_')

```
I think it would be easier to remove the backslash itself:

```
In [165]: df
Out[165]:
  constructed_recipe
0       singl\dzone

In [166]: df['constructed_recipe'] = df['constructed_recipe'].str.replace(r'\\', '')

In [167]: df
Out[167]:
  constructed_recipe
0        singldzone

```