input: Write a function to find the line number in a large document where a given word is present. The function should return the line number as an integer. If the word is not found, return -1.
  assert findWord('This is the first line of the document.\nThis is the second line of the document.\nThis is the third line of the document.', 'second')==2
  assert findWord('This is another document.\nSearch for the word here.\nThat word is not here.', 'word')==2
  assert findWord('This document has no target word.', 'nonexistent')==-1
  assert findWord('', 'anything')==-1
  assert findWord('Final test to ensure.\nAll lines are checked.', 'checked')==2
output: def findWord(document, word):
      lines = document.split('\n')
      for i, line in enumerate(lines):
          if word in line:
              return i + 1
      return -1