def check_serie_is_number(serie, max_serie=5000):
    """Check if serie is valid and return boolean.
    
    Check if serie is a integer and if so if it is not
    a made up number for research. First check if it can 
    be converted to a integer and if so check if it has a 
    smaller value than max_serie. Sometimes a serie
    gets a follow letter (e.g. 400B, 400C) so perform the 
    same checks minus the last character in serie.
    """
    is_number = True
    try:
        int(serie)
    except ValueError:
        is_number = False
    else:
        is_number = int(serie) < max_serie
    try:
        int(serie[:-1])
    except ValueError:
        is_number = False
    else:
        is_number = int(serie[:-1]) < max_serie        
    return is_number