import re


def find_at(text):
    """
    @ - Used to mention someone in tweets

    Parameters
    ----------
        text: str
            Text selected to apply transformation

    Examples:
    ---------
    ```python
    sentence="@David,can you help me out"
    find_at(sentence)
        >>> 'David'
    ```
    """
    line = re.findall(r'(?<=@)\w+', text)
    return " ".join(line)