def check_input(expr, inp, chk, varname):
    """Simple wrapper to test the validity of an input
    
    Arguments:
    - expr: the assessed expression (must be TRUE or FALSE)
    - inp: the input value. It should have a way to be converted to a `str`.
    - varname (str): the name of the input variable
    - chk (str): a human-readable string of acceptable(s) inputs

    Returns: None
    """
    if not expr:
        raise TypeError("ERROR (Invalid setting): '{}'={}. '{}' must be {}"
            .format(varname, inp, varname, chk))
