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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]
```
if self.local:
            command_name = 'lgroupdel'
        else:
            command_name = 'groupdel'
        cmd = [self.module.get_bin_path(command_name, True), self.name]
        return self.execute_command(cmd)
    def _local_check_gid_exists(self):
        if self.gid:
            for gr in grp.getgrall():
                if self.gid == gr.gr_gid and self.name != gr.gr_name:
                    self.module.fail_json(msg="GID '{0}' already exists with group '{1}'".format(self.gid, gr.gr_name))
    def group_add(self, **kwargs):
        if self.local:
            command_name = 'lgroupadd'
            self._local_check_gid_exists()
        else:
            command_name = 'groupadd'
        cmd = [self.module.get_bin_path(command_name, True)]
        for key in kwargs:
            if key == 'gid' and kwargs[key] is not None:
                cmd.append('-g')
                cmd.append(str(kwargs[key]))
                if self.non_unique:
                    cmd.append('-o')
            elif key == 'system' and kwargs[key] is True:
                cmd.append('-r')
        cmd.append(self.name)
        return self.execute_command(cmd)
    def group_mod(self, **kwargs):