input: Write a python function to return words with a length greater than or equal to a specified value.
  assert search_by_length(['apple', 'toy', 'trees'], 5) == ['apple', 'trees']
  assert search_by_length(['car', 'bike', 'bus', 'train'], 4) == ['bike', 'train']
  assert search_by_length(['cat', 'dog', 'fish', 'elephant'], 3) == ['cat', 'dog', 'fish', 'elephant']
output: def search_by_length(words, length):
      return [word for word in words if len(word) >= length]