Where is define this function groups_get_group_tool_options in groups plugin

Hi guys,

I'm going to develop a plugin that extends some functionality of the Groups plugin. but I have a problem when i develop , so When I disable the groups plugin, I have fatal error that appear when I want to access the form of my plugin. when i look the error log of apache the error is on this function groups_get_group_tool_options.

My question is that, please i want know where this function is define in the groups plugin or in elgg, to redefine it in my plugin.

please help me,

regards,
@foka_patrick