locale from environment
  print 1.23 : 1.23
  parse "12345.6789" : 12345.6789
  roundtrip 1.23 : 1.23
locale nl_NL
  print 1.23 : 1.23
  parse "12345.6789" : 12345.6789
  roundtrip 1.23 : 1.23
locale POSIX
  print 1.23 : 1.23
  parse "12345.6789" : 12345.6789
  roundtrip 1.23 : 1.23