docs: def get_field(self, offset, length, format):
          """Returns unpacked Python struct array.
  
          Args:
              offset (int): offset to byte array within structure
              length (int): how many bytes to unpack
              format (str): Python struct format string for unpacking
  
          See Also:
              https://docs.python.org/2/library/struct.html#format-characters
          """
          return struct.unpack(format, self.data[offset:offset + length])[0]