Gets a list of groups within a given account.

		>>> clc.v2.Group.GetAll("wa1-4416")
		[<clc.APIv2.group.Group object at 0x1065b0190>, <clc.APIv2.group.Group object at 0x1065b0dd0>]

def GetAll(root_group_id,alias=None,session=None):
		"""Gets a list of groups within a given account.

		>>> clc.v2.Group.GetAll("wa1-4416")
		[<clc.APIv2.group.Group object at 0x1065b0190>, <clc.APIv2.group.Group object at 0x1065b0dd0>]

		"""
		if not alias:  alias = clc.v2.Account.GetAlias(session=session)

		groups = []
		for r in clc.v2.API.Call('GET','groups/%s/%s' % (alias,root_group_id),{}, session=session)['groups']:
			groups.append(Group(id=r['id'],alias=alias,group_obj=r,session=session))

		return(groups)