import re


def ip_add(string):
    """
    Extract IP address from text.

    Parameters
    ----------
        string: str
            Text selected to apply transformation.

    Examples:
    ---------
    ```python
    sentence="An example of ip address is 125.16.100.1"
    ip_add(sentence)
        >>> ['125.16.100.1']
    ```
    """
    text = re.findall('\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}', string)
    return text