example

import random

words = ['colossal', 'sheet', 'fill', 'modern', 'sulky', 'appear', 'dependent', 'argue', 'potato', 'eatable', 'talk', 'coat']

# generate random sentences from above words
total = []
for x in range(10):
    sentence = [random.choice(words) for x in range(random.randrange(5, 8))]
    sentence = ' '.join(sentence).capitalize()
    total.append(sentence)
    
total_str = '. '.join(total)
print(total_str)

# extract unique words
unique = [item.strip('.').lower() for item in total_str.split()]
unique = sorted(set(unique))
unique_str = ', '.join(unique)
print('---'*10)
print('unique words: {}'.format(unique_str))