code: def header_length(bytearray):
      """Return the length of s when it is encoded with base64."""
      groups_of_3, leftover = divmod(len(bytearray), 3)
      # 4 bytes out for each 3 bytes (or nonzero fraction thereof) in.
      n = groups_of_3 * 4
      if leftover:
          n += 4
      return n
  
imports: from base64 import b64encode
  from binascii import b2a_base64, a2b_base64
label_desc: Use image node_id 1 for calling a global function with example usage: header_length(bytearray) and returns: n