def is_string(a):
    """
    Returns if given :math:`a` variable is a *string* like variable.

    Parameters
    ----------
    a : object
        Data to test.

    Returns
    -------
    bool
        Is :math:`a` variable a *string* like variable.

    Examples
    --------
    >>> is_string("I'm a string!")
    True
    >>> is_string(["I'm a string!"])
    False
    """

    return True if isinstance(a, str) else False