input: Write a function to transform a list of numbers using a given transformation function and return their sum.
  assert transform_sum([1, 2, 3, 4], lambda x: x * 2) == 20
  assert transform_sum([5, 10, 15], lambda x: x + 1) == 33
  assert transform_sum([2, 4, 6], lambda x: x ** 2) == 56
output: def transform_sum(numbers, transform):
      return sum(transform(x) for x in numbers)