def validate_input(name):
    """Check that the user supplied name conforms to our standards.

    A name should be between 1-10 characters (inclusive) and composed of all
    alphabetic characters.

    Args:
        name (str): The name to be validated.

    Returns:
        An error message if the name is invalid, otherwise None.
    """
    if name is None:
        return "You must supply a name!"
    if len(name) > 10:
        return "Your party name is too long!"
    if len(name) < 1:
        return "Your party name must be at least 1 letter!"
    if not name.isalpha():
        return "Your party name must consist of alphabetic characters only!"