input: Write a function to generate a random string of a given length using lowercase letters. The function should take the length as an input parameter and return the generated string.
  import random
  import string
  
  def random_string(length):
      letters = string.ascii_lowercase
      return ''.join(random.choice(letters) for i in range(length))
  
  assert random_string(6) in string.ascii_lowercase*6, "Generated string should be of length 6 and composed of lowercase letters."
  assert len(random_string(6)) == 6, "Length of the generated string should be 6."
  assert random_string(0) == "", "Generated string should be empty for length 0."
output: import random
  import string
  
  def random_string(length):
      letters = string.ascii_lowercase
      return ''.join(random.choice(letters) for i in range(length))