input: 
  from typing import List
  
  
  def remove_punctuations(sentences: str) -> str:
      """ Remove all punctuations from the given string of sentences.
      >>> remove_punctuations("This is a sample string!")
      'This is a sample string'
      """
  
output:     import string
      return ''.join([char for char in sentences if char not in string.punctuation])