text: ## a class for random graph generation
  import networkx as nx
  import numpy as np
  from .multinet import *
  
  def random_multilayer_ER(n,l,p,directed=False):
      """ random multilayer ER """
  
      if directed:
          G = nx.MultiDiGraph()
      else:
          G = nx.MultiGraph()
          
      network = nx.fast_gnp_random_graph(n, p, seed=None, directed=directed)
      layers = dict(zip(network.nodes(),np.random.randint(l, size=n)))
      for edge in network.edges():
          G.add_edge((edge[0],layers[edge[0]]),(edge[1],layers[edge[1]]),type="default")
      
      ## construct the ppx object
      no = multi_layer_network(network_type="multilayer").load_network(G,input_type="nx",directed=directed)
      return no
          
      
      
  