'Returns an integer value from a v1 Value.
Args:
v1_value: a googledatastore.Value
Returns:
an integer
Raises:
InvalidConversionError: if the value doesn\'t contain an integer value'

def __get_v1_integer_value(self, v1_value):

    check_conversion(v1_value.HasField('integer_value'), 'Value    does    not    contain    an    integer    value.')
    return v1_value.integer_value
