def compare_all(self, formatter, in_out):
for input, output in in_out:<EOL><INDENT>self.compare(formatter, input, output)<EOL>self.compare(formatter, -input, "<STR_LIT:->" + output[<NUM_LIT:1>:])<EOL><DEDENT>
Parameters:
-----------
formatter: EngFormatter under test
in_out: list of tuples. Each tuple = (number, expected_formatting)

It is tested if 'formatter(number) == expected_formatting'.
*number* should be >= 0 because formatter(-number) == fmt is also
tested. *fmt* is derived from *expected_formatting*