title: Return multiple lists in Python function
body: <p>I am new to Python, and am trying to create a function which creates lists with different material parameters from user inputs as shown in the code below.</p>
  
  <pre><code>def material():
      layers = int(raw_input("State the number of material layers in the wall (0 for default material): "))
  
      rho = [] # Density [kg/m3]
      c = [] # Heat capacity [J/(kg K)] 
      k = [] # Heat conductivity [W/(m K)]
      #a = [] # Thermal diffusivity [m2/s]
      d = [] # Thickness of material [m]
  
      # Saveing material properties
      if layers == 0:
          rho.append(2300)
          c.append(900)
          k.append(1.6)
          d.append(3.2)
          layers = 1
  
      else:
          for i in range(layers):
              print "\n" "Define thermal properties for material", i+1,"(starting from left)"
              rho.append(float(raw_input("Density [kg/m3]: ")))
              c.append(float(raw_input("Heat capacity [J/(kg K)]: ")))
              k.append(float(raw_input("Heat conductivity [W/(m K)]: ")))
              d.append(float(raw_input("Thickness [m]: ")))
  
      return ???
  </code></pre>
  
  <p>How should I return <em>rho, c, k, d</em> and <em>layers</em> so I am able to e.g. print – or use the value of – e.g. the second item in the list of <em>d</em>?</p>
  
  <pre><code>print d[1]
  </code></pre>