input: Write a function to search for a given word in a large document. The function should return the line number of the document where the word is found. If the word is not found, return -1.
  
  assert findWord('This is a test.\nAnother line here.\nAnd another one.', 'test') == 1
  assert findWord('First line.\nSecond line.\nThird line.', 'line') == 1
  assert findWord('No match here.\nKeep searching.\nEnd of text.', 'find') == -1
  assert findWord('', 'search') == -1
  assert findWord('Single line document.', 'document') == 1
output: def findWord(document, word):
      lines = document.split('\n')
      for i, line in enumerate(lines):
          if word in line:
              return i + 1
      return -1