input: Write a python function to generate a 6-character SHA-1 hash of a given string.
  assert generate_hash("Code Generation Task Instructions") == "8d41db"
  assert generate_hash("hello world") == "2aae6c"
  assert generate_hash("hash me please") == "3cb7e1"
output: import hashlib
  
  def generate_hash(input_string):
      sha1_hash = hashlib.sha1(input_string.encode()).hexdigest()
      return sha1_hash[:6]