input: Write a function to determine the most common fruit name from a given list of fruit names. If the list is empty, return None.
  
  def most_common_fruit(fruit_list):
  
      if not fruit_list:
          return None
  
      # Dictionary to get count of each fruit
      freq_dict = {}
   
      # Count frequency of each fruit
      for fruit in fruit_list:
          if fruit in freq_dict:
              freq_dict[fruit] += 1
          else:
              freq_dict[fruit] = 1
   
      # Get maximum frequency 
      max_freq = max(freq_dict.values())
   
      # Get the most common fruit
      for fruit, freq in freq_dict.items():
          if freq == max_freq:
              return fruit
              
  assert most_common_fruit(['Apple', 'Orange', 'Apple', 'Pineapple', 'Grape', 'Apple'])=='Apple'
  assert most_common_fruit(['Apple', 'Orange', 'Apple', 'Orange', 'Grape', 'Apple'])=='Apple'
  assert most_common_fruit(['Banana', 'Banana', 'Banana', 'Banana'])=='Banana'
  assert most_common_fruit(['Apple', 'Orange', 'Grape', 'Pineapple'])=='Apple'
  assert most_common_fruit([])==None
output: def most_common_fruit(fruit_list):
      if not fruit_list:
          return None
  
      freq_dict = {}
   
      for fruit in fruit_list:
          if fruit in freq_dict:
              freq_dict[fruit] += 1
          else:
              freq_dict[fruit] = 1
   
      max_freq = max(freq_dict.values())
   
      for fruit, freq in freq_dict.items():
          if freq == max_freq:
              return fruit