parameters: (self, idx)
docstring: Set the current group to be idx: now new task generators will be added to this group by default::
  
  			def build(bld):
  				bld(rule='touch ${TGT}', target='foo.txt')
  				bld.add_group() # now the current group is 1
  				bld(rule='touch ${TGT}', target='bar.txt')
  				bld.set_group(0) # now the current group is 0
  				bld(rule='touch ${TGT}', target='truc.txt') # build truc.txt before bar.txt
  
  		:param idx: group name or group index
  		:type idx: string or int
docstring_summary: Set the current group to be idx: now new task generators will be added to this group by default::
docstring_tokens: Set the current group to be idx : now new task generators will be added to this group by default ::
function: def set_group(self, idx):
  		"""
  		Set the current group to be idx: now new task generators will be added to this group by default::
  
  			def build(bld):
  				bld(rule='touch ${TGT}', target='foo.txt')
  				bld.add_group() # now the current group is 1
  				bld(rule='touch ${TGT}', target='bar.txt')
  				bld.set_group(0) # now the current group is 0
  				bld(rule='touch ${TGT}', target='truc.txt') # build truc.txt before bar.txt
  
  		:param idx: group name or group index
  		:type idx: string or int
  		"""
  		if isinstance(idx, str):
  			g = self.group_names[idx]
  			for i in range(len(self.groups)):
  				if id(g) == id(self.groups[i]):
  					self.current_group = i
  		else:
  			self.current_group = idx
function_tokens: def set_group ( self , idx ) : if isinstance ( idx , str ) : g = self . group_names [ idx ] for i in range ( len ( self . groups ) ) : if id ( g ) == id ( self . groups [ i ] ) : self . current_group = i else : self . current_group = idx