def is_number(arg: str) -> bool:
    """Check if a given string can be converted into a number.

    ```python
    x = fe.util.is_number("13.7")  # True
    x = fe.util.is_number("ae13.7")  # False
    ```

    Args:
        arg: A potentially numeric input string.

    Returns:
        True iff `arg` represents a number.
    """
    try:
        float(arg)
        return True
    except (ValueError, TypeError):
        return False