input: from typing import List
  
  def concatenate_strings(strings: List[str]) -> str:
      """Concatenate list of strings into a single string with spaces in between each string.
      >>> concatenate_strings(["Hello", "World"])
      'Hello World'
      """
      return " ".join(strings)
output:     result = ""
      for s in strings:
          result += s + " "
      return result.strip()