def validate_integer(option, value):
    """Validates that 'value' is an integer (or basestring representation).
    """
    if isinstance(value, integer_types):
        return value
    elif isinstance(value, string_type):
        try:
            return int(value)
        except ValueError:
            raise ValueError("The value of %s must be "
                             "an integer" % (option,))
    raise TypeError("Wrong type for %s, value must be an integer" % (option,))
Validates that 'value' is an integer (or basestring representation).
    
stackoverflow/venv/lib/python3.6/site-packages/pymongo/common.py