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<!--- Also test if the latest release and devel branch are affected too -->
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##### SUMMARY
<!--- Explain the problem briefly below, add suggestions to wording or structure -->
group module return values are undocumented.
<!--- HINT: Did you know the documentation has an "Edit on GitHub" link on every page ? -->

##### ISSUE TYPE
- Documentation Report

##### COMPONENT NAME
<!--- Write the short name of the rst file, module, plugin, task or feature below, use your best guess if unsure -->
group
##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.9.0
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/aschultz/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.7.3 (default, Apr 09 2019, 05:18:21) [GCC]
```
cmd = [self.module.get_bin_path('addgroup', True)]
        if self.gid is not None:
            cmd.extend(['-g', str(self.gid)])
        if self.system:
            cmd.append('-S')
        cmd.append(self.name)
        return self.execute_command(cmd)
    def group_del(self):
        cmd = [self.module.get_bin_path('delgroup', True), self.name]
        return self.execute_command(cmd)
    def group_mod(self, **kwargs):
        
        info = self.group_info()
        if self.gid is not None and self.gid != info[2]:
            with open('/etc/group', 'rb') as f:
                b_groups = f.read()
            b_name = to_bytes(self.name)
            b_current_group_string = b'%s:x:%d:' % (b_name, info[2])
            b_new_group_string = b'%s:x:%d:' % (b_name, self.gid)
            if b':%d:' % self.gid in b_groups:
                self.module.fail_json(msg="gid '{gid}' in use".format(gid=self.gid))
            if self.module.check_mode:
                return 0, '', ''
            b_new_groups = b_groups.replace(b_current_group_string, b_new_group_string)
            with open('/etc/group', 'wb') as f:
                f.write(b_new_groups)
            return 0, '', ''
        return None, '', ''
class AlpineGroup(BusyBoxGroup):