title: Python ttk.Button -command, runs without button being pressed
body: <p>I'm making a small script in python with ttk and I have a problem where a function runs where it shouldn't. The button code looks as follows:</p>
  
  <pre>
  btReload = ttk.Button(treeBottomUI, text="Reload", width=17, command=loadModelTree(treeModel))
  btReload.pack(side="left")
  </pre>
  
  <p>and the function is as this:</p>
  
  <pre>
  def loadModelTree(tree):
      print ("Loading models...")
      allModels = os.listdir(confModPath)
      for chunk in allModels:
          ...
  </pre>
  
  <p>For some reason, the function runs without the button being pressed. Why?</p>