code: def update(path,value,timestamp=None):
    
    value = float(value)
    fh = None
    try:
      fh = open(path,'r+b')
      return file_update(fh, value, timestamp)
    finally:
      if fh:
        fh.close()
docs: update(path,value,timestamp=None)
  
  path is a string
  value is a float
  timestamp is either an int or float