title: Index of for loop not iterating correctly
body: <p>I have a for loop that is supposed to iterate a number of times equal to the length of an array. The loop runs the correct number of times, but the index does not properly increment.</p>
  
  <p>I tried manually incrementing i with i = i + 1, but that did not seem to change anything.</p>
  
  <pre><code>room = [['x','x','x','x','x'],['x','.','.','.','x'],['x','.','.','.','x'],['x','.','.','.','x'],['x','x','x','x','x']]
  entities = []
  
  class Entity:
      def __init__(self, x_pos, y_pos):
          self.x_pos = x_pos
          self.y_pos = y_pos
  
          self.new_x_pos = x_pos
          self.new_y_pos = y_pos
      def Move(self, x_move, y_move):
          self.new_y_pos = self.y_pos + y_move
          self.new_x_pos = self.x_pos + x_move
          if self.CheckCollision(self) is True:
              print("collision")
          if self.CheckCollision(self) is False:
              self.new_x_pos = self.x_pos
              self.new_y_pos = self.y_pos
      def CheckCollision(self, entity1):
          for i in range(len(entities)-1):
              #this loop here. It runs twice, but the value of i is zero for both iterations
              entity = entities[i]
              print(i)
              if entity1.new_y_pos == entity.y_pos:
                  if entity1.new_x_pos == entity.x_pos:
                      return True
                      break
              else:
                  return False
  calipso = Entity(1, 1)
  entities.append(calipso)
  joseph = Entity(3,2)
  entities.append(joseph)
  print(entities)
  calipso.Move(1,1)
  
  print(calipso.x_pos, calipso.y_pos, sep=' ')
  </code></pre>
  
  <p>I want i to increment each iteration of the for loop, thus i === 0 for the first iteration and i === 1 for the second iteration. Currently, i === 0 for both iterations and I don't know why.</p>