'Validates the given 1-based page number.
Override to stop checking if we have gone to far since that requires
knowing the total number of pages.'

def validate_number(self, number):

    try:
        number = int(number)
    except ValueError:
        raise PageNotAnInteger('That    page    number    is    not    an    integer')
    if (number < 1):
        raise EmptyPage('That    page    number    is    less    than    1')
    return number
