input: def concatenate_strings(strings, separator):
      """
      Concatenates all elements in the list of strings with the given separator and returns the result.
      
      >>> concatenate_strings(["Sample", "Text", "Hello"], "-")
      'Sample-Text-Hello'
      """
output:     result = ""
      for i, s in enumerate(strings):
          result += s
          if i < len(strings) - 1:
              result += separator
      return result