'Each line as a JSON object with a trailing comma.  Blobs are
output as base64 encoded strings.  You should be using UTF8
output encoding.'

def output_json(self, header, line):

    if header:
        self._output_json_cols = line
        return
    fmt = (lambda x: self.colour.colour_value(x, self._fmt_json_value(x)))
    out = [('%s:    %s' % (self._fmt_json_value(k), fmt(line[i]))) for (i, k) in enumerate(self._output_json_cols)]
    self.write(self.stdout, (('{    ' + ',    '.join(out)) + '},\n'))
