docs: def bars(n=3,n_categories=3,prefix='category',columns=None,mode='abc'):
  	"""
  	Returns a DataFrame with the required format for 
  	a bar plot
  
  	Parameters:
  	-----------
  		n : int
  			Number of points for each trace
  		n_categories : int
  			Number of categories for each point
  		prefix : string
  			Name for each category
  		columns : [str]
  			List of column names
  		mode : string
  			Format for each item
  				'abc' for alphabet columns
  				'stocks' for random stock names
  	"""		
  	categories=[]
  	if not columns:
  		columns=getName(n,mode=mode)
  	for i in range(n_categories):
  		categories.extend([prefix+str(i+1)])
  	data=dict([(x,np.random.randint(1,100,n_categories)) for x in columns])
  	return pd.DataFrame(data,index=categories)