input: Write a function that takes a list of strings and a separator/delimiter as parameters, and returns the concatenation of all the elements with the specified separator.
  
  def concatenate_strings(strings, separator):
   return separator.join(strings)
  
  assert concatenate_strings(["Sample","Text","Hello"], "-") == "Sample-Text-Hello"
output: def concatenate_strings(strings, separator):
   return separator.join(strings)