Search for packages.

def search(self, regex=None, spec=None, **kwargs):
        """Search for packages."""
        cmd_list = ['search', '--json']

        if regex and spec:
            raise TypeError('conda search: only one of regex or spec allowed')

        if regex:
            cmd_list.append(regex)

        if spec:
            cmd_list.extend(['--spec', spec])

        if 'platform' in kwargs:
            cmd_list.extend(['--platform', kwargs.pop('platform')])

        cmd_list.extend(
            self._setup_install_commands_from_kwargs(
                kwargs,
                ('canonical', 'unknown', 'use_index_cache', 'outdated',
                 'override_channels')))

        return self._call_and_parse(cmd_list,
                                    abspath=kwargs.get('abspath', True))