def _isint(this_num):
    """
    Function:
        Test whether a string (usually unicode) is an integer. 
    
    Args:
        this_num (str): The number of tracks the user requests for an artist.
    
    Returns:
        is_int (boolean): Is the input string an integer.
    """
    try:
        int(float(this_num)) # Sometime int(this_name) gives an error.
        is_int = True
    except ValueError:
        is_int = False
    return is_int