title: struct.error: unpack requires a buffer of 4 bytes
body: <p>I want to convert data from a device from bites to float
  I use the code from this answer</p>
  <p><a href="https://stackoverflow.com/questions/5415/convert-bytes-to-floating-point-numbers-in-python">bytes to float</a></p>
  <pre><code>import struct
  
  byte_file = b'+001.80\r'
  print(type(byte_file))
  
  y = struct.unpack('f' , byte_file)
  print(y)
  
  </code></pre>
  <p>I get this <code>struct.error: unpack requires a buffer of 4 bytes</code></p>
  <p>The correct outcome should be <code>1.80</code>
  do I need to implement a buffer argument ?</p>