code: def find_lines(filename, **pattern):
      
      if exists(filename):
          with file(filename, 'r') as fp:
              for line in fp:
                  try:
                      data = json.loads(line)
                  except:
                      continue
                  matches = True
                  for key, value in pattern.iteritems():
                      matches = matches and key in data and data[key] == value
                  if matches:
                      yield data
docs: Find a line (JSON-formatted) in the given file where
      all keys in `pattern` are present as keys in the line's
      JSON, and where their values equal the corresponding
      values in `pattern`. Additional keys in the line are
      ignored. If no matching line is found, or if the
      file does not exist, return None.