title: main() coming back as invalid syntax
body: <p>I'm in a very basic intro level programming course and I'm learning functions. My code keeps returning the call to "main()" at the end of my program as a syntax error. Again I'm super bad at this so don't judge all of my mistakes</p>
  
  <pre><code>def main():
      speed = int(input('Enter the speed of the vehicle in mph: '))
      while speed &lt; 0:
          print('Speed must be greater than zero')
          speed = int(input('Enter a valid speed: '))
      time = int(input('Enter the number of hours traveled: '))
      while time &lt; 0:
          print('Time must be greater than zero')
          time = int(input('Enter a valid time: '))
      show_travel(speed,time)
  
  def show_travel(speed,time):
      print('Hours\tDistance Traveled')
      print('----------------------------------------')
      for time in range(1, time + 1):
          distance = speed * time
          print(format(time, "d"), format(distance, "20.2f")
  main()
  </code></pre>
  
  <p>when i run it it returns with main highlighted saying syntax error</p>