title: Accessing params attribute in lmfit
body: <p>I am trying to work through an example using lmfit from the documentation website:</p>
  
  <pre><code>import sys
  
  import numpy as np
  import matplotlib.pyplot as plt
  from matplotlib.patches import Rectangle
  from matplotlib.backends.backend_pdf import PdfPages
  
  from lmfit import minimize, Parameters, Parameter, report_fit, Minimizer, conf_interval, conf_interval2d, printfuncs
  from lmfit import Model
  
  def main():
      def decay(t, N, tau):
          return N*np.exp(-t/tau)
  
      decay_model = Model(decay)
      print decay_model.independent_vars
      for pname, par in decay_model.params.items():
          print pname, par
  
  if ___name___ == "___main___":
      main()
  </code></pre>
  
  <p>When I execute the last command, I get the following error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  AttributeError: 'Model' object has no attribute 'params'
  </code></pre>
  
  <p>It seems that params is not an attribute of Model. Can someone explain why this code does not work? I tried this on multiple computers and versions of Python. Running on Python 2.7.9 32 bit, Windows 7.</p>