input: 
  from typing import List
  
  def concatenate_strings(strings: List[str], separator: str) -> str:
      """ Concatenate all elements in the list with a given separator/delimiter.
      >>> concatenate_strings(["Sample", "Text", "Hello"], " ")
      'Sample Text Hello'
      >>> concatenate_strings(["Sample", "Text", "Hello"], "-")
      'Sample-Text-Hello'
      """
      return separator.join(strings)
  
output:     return separator.join(strings)